I may be wrong (and I quite often am) but I don't think that talking about these things is illegal. It;s the actual act of doing them. You can talk about having sex with animals but unless they catch you at it, I don't think that there is really anything the govenment can do to you.

As for sex with young women, I assume it is the same thing. It's also like wife beating. Unless they catch you in the act, they can't do much for you. In someways, having to be caught red handed, so to speak, is and advantage, but in other ways it sucks.