Nope. He didn't need to. Lefebvre and his four bishops did it to themselves.
Nonsense. To incur excommunication, one must not be able to appeal to a state of necessity or grave fear (which was probable and in fact proven in case of Lefebvre). The appeal made by the Archbishop and Bishop de Castro Mayer in Rome at the Vatican Rota, was never replied to, never processed, and as such the excommunication can already be seen as null and void and never incurred.
However, while the Pope can excommunicate anyone in the entire world, the local bishops can and have to in their dioceses. Therefore, do you still hold St. Jeanne d'Arc died outside of communion with the Catholic Church? She was excommunicated by the French bishops! The authority of a bishop in excommunicating is as large as that of the Pontiff, only with that difference, that the Roman Pontiff can excommunicate all subjects in the entire world and the bishop only inside his diocese.
Martin Luther said the same thing:
Yes, but Martin Luther committed an act that was directed against the FAITH, an act of heresy. An intrinsically evil act can never be excused and always incurs the penalty. That's equally true for the schism caused by the bishops of the Chinese Catholic Patriotic Association in 1957. They were excommunicated not directly for the consecrations of bishops in itself, but because they intended and effectively did, autonomously appoint those bishops to Episcopal Sees in China, which is an infringement upon the privileges and authority of the Pope. That's an intrinsically evil act of schism (they usurped ordinary jurisdiction). The same for the Ultrajectine Jansenist Church of Holland, which in 1723 autonomously appointed the illicitly ordained bishop Cornelius van Steenoven to the exempt Archdiocesan See of Utrecht, another infringement upon the prerogatives of the Popes, and an act of schism (usurpation of ordinary jurisdiction and a see).
But neither of those aspects apply to the Consecration of Bishops by Archbishop Marcel-François Lefebvre CSSp and Bishop Antônio de Castro Mayer in June, 1988. They had begged for years for a bishop to be allowed to be consecrated, they had received permission, they had been frustrated for years and years. They then chose, considering their responsibility in the Church's crisis, to do an intrinsically good act (Sacramentally Ordaining a Bishop is a good act in itself, part of the Sacrament of Orders), under grave fear and under honest persuasion to be doing their best, in accordance with Roman Catholic doctrine and discipline.
Final Note: Abp. Lefebvre and Bp. De Castro Mayer only conferred the sacramental episcopal potence, they never appointed or usurped ordinary jurisdiction upon the consecrated, nor did the consecrated later claim to possess such. We are talking merely about the conferral of sacramental grace of bishop and his potence. Not about jurisdiction and schism, which was present in all other instances of illicit episcopal consecration in the past of Church history. It is extremely important to consider this, as it may have occasioned John Paul II (Cardinal Gantin) to act as he did, and having to later to come to see, that none applied, did not want to revert as that could touch his "authority".
They were excused by the follow Canons of the 1983 Codex Iuris Canonici:
Can. 1323 No one is liable to a penalty who, when violating a law or precept:
1ƒ has not completed the sixteenth year of age;
2ƒ was, without fault, ignorant of violating the law or precept; inadvertence and error are equivalent to ignorance
3ƒ acted under physical force, or under the impetus of a chance occurrence which the person could not foresee or if foreseen could not avoid;
4ƒ acted under the compulsion of grave fear, even if only relative, or by reason of necessity or grave inconvenience, unless, however, the act is intrinsically evil or tends to be harmful to souls;
Ordaining bishops is not intrinsically evil, but usurping jurisdiction and creating a parallel Church ís. The latter two things were not committed by Abp. Lefebvre and his ordained bishops.
5ƒ acted, within the limits of due moderation, in lawful self-defense or defense of another against an unjust aggressor;
6ƒ lacked the use of reason, without prejudice to the provisions of canon. 1324, ß1, n. 2 and 1325;
7ƒ thought, through no personal fault, that some one of the circumstances existed which are mentioned in nn. 4 or 5.
Can. 1324 ß1 The perpetrator of a violation is not exempted from penalty, but the penalty prescribed in the law or precept must be diminished, or a penance substituted in its place, if the offence was committed by:
1ƒ one who had only an imperfect use of reason;
2ƒ one who was lacking the use of reason because of culpable drunkenness or other mental disturbance of a similar kind;
3ƒ one who acted in the heat of passion which, while serious, nevertheless did not precede or hinder all mental deliberation and consent of the will, provided that the passion itself had not been deliberately stimulated or nourished
4ƒ a minor who has completed the sixteenth year of age;
5ƒ one who was compelled by grave fear, even if only relative, or by reason of necessity or grave inconvenience, if the act is intrinsically evil or tends to be harmful to souls;
Even for those erroneously thinking consecrating bishops, thus conferring a Sacrament, is intrinsically evil, this says all: excommunication had to be diminished. One cannot reasonably hold, that Abp. Lefebvre was not compelled or felt compelled by grave fear.
6ƒ one who acted in lawful self-defense or defense of another against an unjust aggressor, but did not observe due moderation;
7ƒ one who acted against another person who was gravely and unjustly provocative;
8ƒ one who erroneously, but culpably, thought that some one of the circumstances existed which are mentioned in Can. 1323, nn. 4 or 5;
9ƒ one who through no personal fault was unaware that a penalty was attached to the law or precept;
10ƒ one who acted without full imputability, provided it remained grave.
ß2 A judge can do the same if there is any other circumstance present which would reduce the gravity of the offence.
ß3 In the circumstances mentioned in ß1, the offender is not bound by a latae sententiae penalty.
That really tells us all. And you, Mr Michael, may disagree with me, but the Vatican Tribunal has never dared to respond to this, nor accepted an appeal (which is abuse of judicial powers and grave sin of injustice), many Vatican officials and canonists said, they could not believe excommunication applied. The 1989 Professor of Canon Law of the Pontifical University of Louvain (Leuven), Belgium, quite a Modernist university and NOT a traditionalist professor, told one of his students (an adult Roman Catholic male, judge, lawyer and scientist and former officer in the Dutch Armed Forces): "Don't talk about excommunication! You are not going to believe that document filled with faults and errors, are you? There was no schism, no heresy, and there was grave fear, why an excommunication? None applied, I say to you. They excommunicated a most Roman reactionary there is. That was not done correctly and judicially. Church politics! I say you." That says enough.
You do not have to agree with me, as I have no authority, but I do not agree with the Vatican, on reasonable grounds, and so do numerous Church authorities, professors, canon lawyers. And the Vatican is known for its Church politics penalties in the Lefebvre case all along, as in 1988 it judicially promised a Bishop (sic!) to be ordained by a SUSPENDED (1976) Archbishop for a supposedly EXEMPT (1976) institute of priestly life. That tells you how careful the church politicians handle Ecclesiastical penalties, and how they handled them in this case. Not, or just as a Machine gun to mow down the "Lefebvrists".
We will shortly see a definitive response to this 1988 case, I guess. The SSPX will not take a simple "lifting" of these "excommunications", but will make the demand, that it be declared invalid and not-applying.
There have been a LOT of invalid excommunications by Popes and Bishops in the past (e.g. against Fr. Savonarola O.P., now in process of beatification), the most notable being St. Jeanne d'Arc. Another French native who acted under grave fear, divine compulsion, and received such a penalty. She was made a Saint in 1920. And she was a Saint all along. The canonization by Pope Benedict XV and the beatification by Pope St. Pius X did not free her from hell (as per impossibile), but confirmed her sanctity from the very point of her death, that she was in heaven.