"Betrayal" might be a wrong word for it, but I find this disappointing because the current events are the reason I have tried using Proton instead of Gmail. A tweet wont ruin the functionality of Proton, but it goes against my personal rationale for making the switch.
Many feel betrayed because he (partially at least) politically aligns with someone (and something) they loathe intensely. The feeling of betrayal probably comes from an implied idea that because they align on the issue of digital privacy they naturally do so in other aspects, and with the comments made by the CEO that idea is burst and someone who once felt familiar is now foreign.
Unless I'm missing something, didn't Yen just praise 🍄's pick for antitrust AG? I forget her name, but her Wikipedia page didn't make her sound all that great, so I'm not sure what exactly he was praising her for. If that's all it is (and it might not be!) that hardly sounds like a betrayal.
Praising the pick wasn't so bad. The issues really arose when he was called out on it and chose to use Proton's official accounts to affirm his view and went on to state:
the republican party is now the party of the people and most likely to crack down on big tech
The democrats have effectively betrayed their voters in favour of corporate donations
This was Proton's official stance
It was insane boot licking and incredibly poorly thought through. It's fine for him to have an opinion but completely inappropriate to use their official accounts to spew such drivel and to state it was the official stance should have resulted in him being fired for damaging their reputation.