Ah I see. It's an issue for my use of Protonmail, in that I may cancel and move to another vendor who is more forthright. Here's what I would expect my future vendor to say about this:

"Hey, we respect your needs. However, we have to tell you that you should treat us as a bit of an adversary. We will do what we can as a private company, but ultimately we can be compelled by the government, rogue employee, or if somehow we get hacked. This is the case for any company no matter what they promise or avoid telling you. We do tell you. As our customer, here's what we recommend you do: Use Tor, fund open source, vote, etc."