“There are really only three choices:
1. No, they didn’t. They were bound by tradition as much as the Pope was.
2.Yes, they did, therefore, the perpetual virginity of Mary is consistent with sola scriptura, therefore, Protestants shouldn’t lodge it as an objection to the Catholic faith
3.Sola scriptura really isn’t a sure norm of faith after all.”
You’re missing the 4th option:
Sola scriptura is appropriate for all doctrinal issues concerning salvation and holiness, but the issue of perpetual virginity doesn’t fall into that category. Therefore, Christians can disagree on topics such as this since it doesn’t impact salvation.
I agree to an extent. The problem is that this then moves to rejecting everything that has been believed since Apostolic times like the Eucharist etc.