This has nothing to do with email as a protocol. The court order discussed in the article asked for the recovery email address of an account. No actual email data was transferred.
I'm aware. But some user data and metadata required for email protocol to function that can't be encrypted is the fundamental issue. No provider can solve this issue, no matter how private and secure they are.
In this specific case, the user was a dumbass and linked another email that was tied to Apple. My point was more about email being flawed by design and a need for an alternative protocol if we want true privacy.
It's in the article ffs. The recovery email was managed by Apple, so they made a request to Apple and obtained the users real identitiy. Once they arrest the user they can gain access to all the users accounts — unless the user had specifically guarded themselves against that possibility.
If they could get into the recovery email, yeah, they could get into his Proton account. Also useful just for confirming the ID of the person in question.
It's just a general rule of thumb: privacy and security companies can work well against outside attacks but can only do so much against a government/court order, so don't expect any of them, not even Mullvad, to go to jail for you. Encryption, anonymization and no logging are the most anyone can expect/hope for from a company, which still puts companies like Proton or even Tutanota leagues ahead of the spyware that is Gmail, Yahoo or Microsoft when it comes to email. The end user needs to do the rest themselves.