If you're storing any kind of information you'd rather keep private on a server you do not control and not diving into the policies and blog posts of said provider to make doubly sure they're all they say they are, it's no one's fault but your own when something inevitably happens. Either do your due diligence or blindly accept the risk. People took the second option and look what happened.
And yes, I would say an order from Swiss courts that was unappealable is an extreme criminal case. Anything that could threaten Protonmail qualifies.