I think it's some combination of "fascist logic is not logical" and "we may invent some new ways of subjugating people we don't like".

To add on to the former, the theocrats don't even really want you having sex, either, they just want you to magically have children for the Church or the Army or whatever. Ideally, you can just do the virgin birth thing like Jesus's mom, that worked out well. In-vitro is banned in some places here now (there is also some debate as to whether or not the ban was truly on purpose), so ya can't do that. If you absolutely have to have sex, don't have it more than like once per each child. If you have six kids, hopefully you only had sex six times.

As to the latter, we already have the conservatives demonizing cities, where minorities disproportionately live, with lies about "unprecedented" crime and voter fraud. They've also recently repealed affirmative action, and there's always the classic gerrymandering and voter suppression techniques.

Anyway. I wonder if the onset of free porn has something to do with less sex, too.