Pull the trigger because Protonmail‘s CEO said that they would leave Austria before cooperating with any agencies. They are still in Austria so they have to corporate through the BÜPF.
At the end of the day Protonmail itself is a company and they have to follow some rules to keep their operations running. If you look at their transparency report you'll see that they have been complying with government request, both local and international since 2017
https://protonmail.com/blog/transparency-report/
What you are saying is (of course) correct. But that makes the posturing / marketing of Protonmail no less deceptive if not outright dishonest.
It can indeed be (cynically) argued that Protonmail is just a company like any other, which will just say / claim whatever it thinks it has to, to find itself a slice of the market and make a buck.
Nonetheless and even while that might actually be the case (I'm not sure), in "the good old days" (/sarcasm) citizens still had something like tar and feathers to deal with dishonest business practices. I wonder what do citizens / consumers actually have these days? Please don't respond with: "voting with our feet", because that is not how things work with deceptive marketing.