Others have already touched on the jurisdiction issue.

I'm also going to note, in the last 10 years a lot has changed. E2EE has gone from something that's fringe, to something integrated integrated into lots of products. Signal, Proton, and others launched in the wake of the Snowden revelations. Lavamail was Snowden's email provider.

It's kind of like being the "hipster nerd" playing D&D before D&D was popular vs playing D&D post popularity... It's pretty obvious to most people in 2023 that D&D isn't for demon worshiper, as it's pretty obvious in 2023 that E2EE isn't just for criminals. In other words, the value proposition of ProtonMail isn't as "sinister."

I personally suspect the US Govt (in terms of federal agencies) is adapting to the presence of encryption vs trying to kill or weaken it at every turn (similar to how Microsoft stopped trying to stomp out open source code). 9-11 was a very very very bad thing (and arguably why the US is one of the worst countries to host a privacy service). However, the "big one" when it comes to cyber attacks could be even worse (and I'm pretty sure there are people at NSA that understand how E2EE plays a role in securing the nation -- they're not dumb people after all).

Proton is also a larger company than Lavabit (I suspect), and with that comes lawyers, and money to feed them.

So long as ProtonMail isn't primarily acting to serve organized crime... I suspect "there are bigger fish to fry."