I try to turn it other way in my head, like if Mullvad got to know somehow political views of some of their customers and say "We don't like what you say, so we decide to end our business with you. We don't want our infra to be used to spread opinions like yours."
You’re not taking it far enough. What if Mullvad has someone you disagree with as a customer, and does nothing about it. Does this mean that Mullvad is supporting them? Does this mean that you have to stop supporting Mullvad? What about Mullvad’s landlord? The company that provides them their electricity? Their internet provider? Their internet provider’s internet provider? Should you boycott the entire internet because Mullvad has not been given the BGP death penalty?
If the far-right parties they're supporting are similar to MAGA in the U.S., what they're doing is taking customer money and funneling it into a political effort to do just what you're describing - just in a different way. "We don't like groups X, Y, and Z, so we're going to fund a political effort to take their rights away by using government."
As I understand it, the Örebro party pushes for deporting immigrants and has a "Sweden belongs to the Swedes" policy that includes deportation for even those born in Sweden if their parents were born in, e.g., Somalia. So basically, "we don't like certain people, so we want to use customer money to force them out of our country". That really doesn't paint Mullvad as the victim, here.
They could do it, some people would align with that stance, and some wouldn't. Exactly how it plays out being a customer: now we've discovered he supports a far-right party here in Sweden, I can choose to not support the CEO with my money and let others know about their political leaning to decide by themselves if they want to support him and his business aware that their money might got to far-right parties.
I don't see any issue with your flipped argument, it's the same thing, no?