[pmoriarty]

IANAL, but that just seems to say that under that particular law (SPTT), Internet access providers have to provide the technical means for lawful interception. It does not say that no other entity has to provide the technical means for lawful interception.

In other words, the law does not say that ProtonMail is exempt for having to provide lawful interception. They might still have to do so, based on some other law.

Further, it's quite conceivable that unlawful means (such as blackmail, threats, or bribery) could be used to coerce ProtonMail. That's not to mention perfectly lawful means of enticing them -- like appealing to their patriotism, willingness to help in a critical investigation, or demonstrating some credible threat.