Things like this are in fact happening. From people who've used a bitcoin exchange connected to their Chase bank account to people that are a bit too right leaning for those at Patreon, regardless of where those opinions are expressed. While they allow similar language with a different bent on their actual platform.
When the gatekeepers of money start acting as censors, is that really not as bad or worse than the telephone company doing the same?
Which is exactly the kind of useless functionality that they don't need. Most of the creators I've seen either migrate away from Patreon or diversify themselves end up using payment processing services like Stripe or Paypal.
So says you, yet the vast majority of people I subscribe to on Patreon use it as a delivery platform for advance content to subscribers. One of the major ways it promotes higher donation amounts is by letting those people have gated access to content. How else would this be easily accomplished except for this "useless" functionality? A single password that is handed out? A large list of passwords that the artist needs to manage?
It quickly becomes obvious that this useless functionality has a very real use case, and I think it's in fact one of the drivers of high donation rates in some cases.
In my opinion, Patreon is more akin to a newspaper deciding which ads to show next to their articles or to a shopping mall deciding which shops to rent space to. And of course every newspaper will reject ads that would infuriate their readers (or journalists) and shopping malls will not rent to businesses that might damage their reputation (depending on how "upscale" it is this might be everything from soup kitchens over gambling outfits and payday lenders to brothels).
Now, you might disagree with them whether they have drawn the right line there and consequently take your business elsewhere (just as you might not want to visit a shopping mall with the wrong mix of shops), but I find it a bit of a stretch to frame this as a "free speech" issue.