FWIW, I've never heard anyone so much as suggest that one should put off confession until they can get to a Resistance priest.
I haven't either, I'm just trying to understand the difference between refusing to attend mass as a rule by a priest who is NOT excommunicated, an heretic or a schismatic and going to confession to them.
If we're supposed to trust that God will provide graces to persevere when we refuse one available sacrament, why should we not trust that He will provide the graces from another available sacrament?
Hopefully someone more knowledgeable than I am will answer. But I think part of it is because confession of mortal sins is so utterly necessary for salvation. I've always understood that, if one is on their deathbed, one can confess to
any valid priest. e.g. even an "Orthodox" schismatic*; (similar to how anyone can baptize, whether heretic or infidel, because Baptism is so necessary. ) Whereas, obviously one is not supposed to go to Masses of the "Orthodox". (I think
part of it is because of showing
communion with them? - as I said, hopefully someone else can explain it better) The Church knows that it is very difficult for most people to truly have perfect contrition, and you don't want to risk your salvation on that. Relying on perfect contrition is only when confession is absolutely not available.
I think Fr. Pfeiffer made the distinction in a sermon in the past year, but sorry I can't point you to it.
*obviously assuming he's the only one available. If you have access to a good Catholic priest, obviously you confess to him.