He praised trump for appointing someone into a role who is a big tech sceptic. However the issue is he then went on to make a broad generalisation about the republicans being the party of fhe people and the democrats being by the party of big business. Someone from proton doubled down on the assertion on social media.
That has caused offence in a era when US politics is extremely polarised and divided. The attitude is "if you're for the other team, you're the enemy". But also people are angry at the company having an apparently right wing political stance.
Personally I think this is overblown. I think its reasonable to be happy if someone anti big tech is appointed, but the broad sweeping comments about the parties was ill judged. However they have backed away from this position and made clear that proton in politically neutral. I see this as bad PR and on the spectrum of someone saying something stupid on twitter and then regretting it, but some people are treating it as an existenial threat for proton and a huge red flag.