I think people who argue about sex ed often argue past each other because they have different views of what's most important. Conservative viewpoints tend to respect tradition, authority (e.g. that of fathers over daughters), and traditional purity codes. Liberals tend to be concerned more with enjoyment, protection from harm, and freedom as a "good" in itself.
For an extreme, and so because of that unfair, example, the Christian St Augustine believed consensual homosexual activity to be worse than heterosexual rape. The former violates the natural order of the universe, as he saw it, running contrary to God's intentions for us, and nothing good resulted from it. The latter, though despicable, was consonant with nature, and a good could come of it (another human being).
To the modern ear, even of almost all conservatives, this sounds terrible, simply because we value consent and refusal much, much, more that did Augustine---and we live in a world where there is much more at least formal opportunity to exercise it. Again, I think modern conservatives hate rape...but I think they still have a strong tendency to believe that certain states of sexual experience (virginity vs sexually active) and certain acts (penile-vaginal intercourse v. everything else) define right and wrong in a way they don't to (loosely speaking, given the general tenor of this site, and apologies to those who strongly disagree) "us".
This means that conservatives have a harder time speaking out against rape than we do, because there's a whole slew of activities that they associate with sex that they consider wrong, whereas we mostly just consider rape as the major sexual sin---I'm sure all of us consider intentionally or even negligently spreading an STI to be very bad, and using sex to emotionally manipulate others as well, but if pressed, many of us might resort to calling them 'like rape'.
It's a lot easier stressing the difference between consent and its lack, and claiming the category of 'sex' for a wide variety of acts, when you consider rational consent to be the major determinant of whether an act were right or wrong, and don't really care which particular sex act is involved. If you believe consensual anal sex to be wrong, and rape, and having sex without being married, things become less clear.