It's not the more conservative parents, students, or teachers at that high school that were complaining. Did you read their statement? (Found in other articles online: author of anti-Sr. Jane statement was Emma Winters). These are people who demand that the homosexual condition is to be affirmed and embraced, that active homosexual conduct is a human right, that the Church ought not to teach against homosexual behavior, contraception, divorce, abortion, or any aspect of the spiritual and social disintegration surrounding sexual immorality.
So your hypothesis is incorrect in the light of the arguments made by the anti-Sister-Jane petition (which you can still google, I think, using the search words "Emma Winters" and "Charlotte Catholic High School").
I understand it is those on the left who were offended. My point is that people on the right can be offended too, as the “latency period”, which serves to delay when sex topics should be introduced, was violated by the sister.