What the email provider snitched is the IP address (which wasn’t “tori-fied”). So it was anonymity what was compromised in this case.
The email was openly used for activism so the police was already investigating it, they only wanted to know the identity of the physical person behind it, and that’s what ProtonMail helped with, since the activist didn’t use anonymizers. The police didn’t need to decrypt the contents of the account or compromise its privacy (which is what using ProtonMail would have protected against), just its anonymity.
What the email provider snitched is the IP address (which wasn’t “tori-fied”). So it was anonymity what was compromised in this case.
The email was openly used for activism so the police was already investigating it, they only wanted to know the identity of the physical person behind it, and that’s what ProtonMail helped with, since the activist didn’t use anonymizers. The police didn’t need to decrypt the contents of the account or compromise its privacy (which is what using ProtonMail would have protected against), just its anonymity.