Most people aren’t demanding Mullvad fire the founder,

except they kind of are by saying they're switching because of his donation specifically, which implies to me that those same people would have to think its acceptable for a company to know and have influence over its founders political beliefs or donations. Like what other result are people expecting other then to have him step down from the org (because probably it would be illegal to actually oust them over political donations, so it'd have to be voluntary anyway).

Lets say it was the case for you, you founded a VPN company and turns out your partner is a fascist but you had no idea when it started because it wasnt until 5 years after the founding that they started dropping hints, what would you do? Start a brand new company? You could pressure them to step down privately, you could release a statement saying the company does not support those causes, and you could do everything in your power internally to ensure that person (and really NO person) has access to any kind of logging or things that could expose users (and thats also just practical in terms of keeping your reputation as a VPN provider in tact really). Mullvad has aready done the last bit, any VPN provide worth using would have to be setup in a similar way really.

Benefit of the doubt that you aren’t asking in bad faith.

How would this be in bad faith? I'm saying i think its short sighted because it seems to me they didn't think through the entire consequences of what happens if it gets flipped on you or someone you support, while ignoring the things that would actually put more limitations on their own risks, primarily if you just switch to another VPN provide but dont ALSO stop paying with a card or something linked to your name/bank then you are not actually improving your own situation much.

It's similar to the reaction for Proton "exposing" a customer's payment information, of course i dont agree with them doing it, but I also understand they are a corporation and subject to laws of their country and court orders so the lesson should not be "dont use this VPN provider because they will rat on you" it should be "Dont give VPN providers enough information TO rat on you"