Itch has the option to stand up
They could have made a public stink about all of this, and put the pressure on the right wing groups, but chose not to and to silently cave.
Boycott is the only option. If they don't reverse, they deserve to fail
To add a bit of context - Itch.io previously had delayed payments without this whole thing going because of spam. This will just accelerate devs not being paid because they have to check which games can be allowed to pay in the first place. It's not so easy as "we will pay everyone until we figure out which games we can take down" as payment processing companies wanted immediate results. Steam didn't have discussions with the devs either, neither had DLSite nor platforms like Patronite when they were limiting what can be allowed on the platform.
itch's mistake is the way they handled all of this. But the whole fiasco is payment processors and Collective Shout' fault and they should get most of the blame.
Unfortunately, the all-powerful Steam also caved... That's going to be a tough battle.
Short term solution? Publish games on other platforms that are more friendly towards adult-themed games (easiest, but many of those platforms stinks) or self-host them and sell them yourself (difficult and expensive for most, requires legal advice).
Collective Shout is, in my opinion, just a front. People have been looking into it and found that CS has been around for over ten years, has never once succeeded in anything they attempted to do (they have been caught in many lies just like PETA has), has no financial backing, and doesn't even make 1k hits to their website a month. Suddenly, their backing went from next to nothing (none from government, which most organizations get from) to several million dollars. Also, CS is a group of 10 people and Visa and Mastercard would be losing billions on refusing these transactions, so whatever pushed them had to be something more than financial threat from a handful of people. There is clearly another entity at large here.
To add to the right wing comment, this exact push for censorship was detailed in Trump's Project 2025. Whether it is a coincidence or not, however, I can't say, but it is something to keep in mind.