'I would suggest that since a woman wearing women's slacks can be easily distinguished from a woman wearing men's trousers, that this argument can be dismissed.'
I would suggest that there is absolutely no difference between a woman wearing 'women's slacks' and one wearing trousers.
'I would suggest that if all pants on women are immodest, that either a reason that appolies only to women needs to be brought up, or that trousers would also be immodest on men.'
A. Trousers are not, generally speaking, immodest on men.
B. The reason that all pants are immodest on women is that wearing pants is not feminine and does not promote a traditional feminine identity, esp. vis a vis a traditional masculine identity.
'And I would suggest that there are 2 points against the last argument: 1. women are no longer necessarily wearing slacks because of a rebellious nature,...'
I would suggest that they are.
Proof: Tell women to stop wearing pants. Even 'traditional Catholic' ones.
Observe the results.
'...which would bring us back to whether slacks are inherently immodest;...'
On women, yes. On men, not necessarily.
'...and 2. unless we take his comments about lengths of skirts (8 inches below the knee) and sleeves just as seriously, then we are thinking he was writing from a chrono-centric point of view and just using his comments about slacks to bolster an argument about them.'
'Chrono-centric'. Oh my... Tradition itself is 'chrono-centric'! Now we're going to dismiss a traditional practice because it is 'chrono-centric'?
I hope someone passes me whatever it is that everyone appears to be smoking. It must be good: all I have is regular tobacco...