I am not sure why anyone would use an AI code editor if they aren’t planning on vibe coding.

Vibe coding means only looking at the results of running a program generated by an agentic LLM tool, not the program itself - and it often doesn't work well even with current state-of-the-art models (because once the program no longer fits in the context size of the LLM, the tools often struggle).

But the more common way to use these tools is to solve smaller tasks than building the whole program, and having a human in the loop to review that the code makes sense (and fix any problems with the AI generated code).

I'd say it is probably far more likely they are using it in that more common way.

That said, I certainly agree with you that some of Proton's practices are not privacy friendly. For example, I know that for their mail product, if you sign up with them, they scan all emails to see if they look like email verification emails, and block your account unless you link it to another non throw-away email. The CEO and company social media accounts also heaped praise on Trump (although they tried to walk that back and say it was a 'misunderstanding' later).