> Even dumber, from their perspective, because there are a mountain of historical rulings that say porn is not protected by free speech.

There are a mountain of historical rulings saying that obscenity isn’t protected speech, but the sonewhat fuzzy legal definition if obscenity is (at least in its normal application) narrower than the commom term “pornography”. Moreover, and more specifically related, mandatory age verification laws for adult content online have been struck down twice by the US Supreme Court as First Amendment violations, first when it struck them down as part of striking down most of the Communications Decency Act of 1996 (leaving Section 230 intact but pretty much nothing else from that law), and again when it struck down the Child Online Protection Act of 1998.

EDIT: Correction: COPA was struck down by a Court of Appeals and the Supreme Court declined to hear the government’s appeal, there was no Supreme Court ruling on the merits; the end result is the same, but only the CDA was actually struck down at the Supreme Court level.