Maybe Bishop Fellay is the the only good apple of the four? Just putting it out there...
The SSPX is faced with 3 choices. First, is the sede option. No discussion on that, it is obvious what that entails.
The second is open schism. Up to now the SSPX has had a good argument that they were sent into exile. They didn't leave. They were kicked out. So it is a reasonable argument that they were not schismatic. You may disagree, but it is at least a reasonable argument. But now things have changed. The Pope has evidently called them back. He has lifted the excommunications, and I'll assume he is setting up a structure where the SSPX can continue in its mission to provide the Traditional sacraments without being molested. To deny this is to embrace schism, that is, to separate yourself from the authority of the Pope. Now there are PRACTICAL reasons to be cautious. But to separate yourself from the Pope no matter what is schism. And even separating yourself over PRACTICAL reasons is arguably schism.
The third option is to confess that the Church is the Church, and the Pope is the Pope. That is the option Bishop Fellay has chosen, and that makes him a "good apple".
However, Bishop Fellay does not have clean hands in this, and I see some justice. While he has been the ruler of the SSPX, he has allowed the official policy of the SSPX to state that the faithful should avoid FSSP Masses due to mythical sermons preaching how wonderful Vat. II is. So if the laity is on vacation, and there is an FSSP chapel nearby, the official policy of the SSPX, even today, is that this person should avoid the sacraments. If the laity that attend the SSPX Masses had followed this, then they would also have avoided the Pontifical High Mass that was given by Bishop Slattery in D.C. That is how absurd it is, and yet Fellay allowed it.
So now he is going to go back to the laity who attend the SSPX Mass and tell them that he now wants to be reintegrated into the official structure. Is it any surprise that he will face rebellion. I agree it must be done to avoid schism, but I am not surprised at the rebellion.