The ulterior motive is this sort of payment neutrality also means hate groups can't be blocked by payment processors unless the actively do illegal shit.
You kinda have to make that judgement call if you think that's an acceptable cost for keeping porn from being censored.
Of course, there's nothing stopping these payment processors from continuing to ban porn while allowing hate groups to exchange funds as tolerating hate has recently become more popular. It's entirely their whim we're up to.
It's a shitty situation to make a choice on, but personally I don't like all of this being subject to the whims of private companies who can be swayed by a thousand weirdos. That's just madness making.