It seems like the Respect for Marriage'ish Act will either sooner or later be used as a cudgel to beat the Church into hosting or performing marriage-like acts between people of the same sex as well as other wonky innovations.

I have a friend who though not Catholic is sympathetic towards the Catholic Church. He believes that in time, pushed strongly forward because of this Act, that the Church will be forced to either acquiesce with the State or give up its tax exempt status.... and there by more truly unfettering the Church allowing it to be more concerned (in its impoverished state) with the salvation of a fallen nation.

Has there been a Catholic politician who has done more (abortion and fake-marriage) to hurt the Catholic Church than Joe Biden?

1) Yes, certain factions in the US will certainly use this law to try and force Churches to perform homosexual union ceremonies. That ultimately is the attempt (although the law is disguised as protections for what is already legal in most states already and those laws have already passed SCOTUS muster). That's why many who opposed tried to get the law amended to protect religious liberty.

2) The SCOTUS will almost certainly strike down the law if it is used to force religious institutions to perform these ceremonies and they are opposed. The Court in general, even when it was leaning different politically than it is today, generally protected Churches. Generally, but not always.

Remember in 2020 Pete Buttigieg promised he would revoke the tax-exempt status of any church that refused to perform gay marriages. This is indeed the endgame, liberals always make a veneer of persuasion but ultimately resort to force when people remain unpersuaded. This is also why the very people who used to claim to be free speech 'absolutists' now openly call for government censorship.