When homosexual acts were legally considered "unnatural" and illegal, same sex porn was not outright illegal or "obscene".
Yet when the age of consent is under 18 (16, 17) or bestiality is legal (and it is/was legal in a number of states) you could engage in the acts, you just couldn't film/photograph them.
None of the distinctions make sense.
And yet public school teachers can pretty much pick and choose what they want to tell your kids about anal cucumber sex between men and goats or anything else. It’s a public health issue, after all!