Protonmail did not provide the authorities with the users IP address...they did allow the account to monitored which they are required by their laws to allow. It was the users sloppy OPSEC that allowed the authorities to eventually track them down. In the end, I believe, it was linking the user to a past Gmail account that finally did him in. Listen to this podcast episode, the presenter does a fairly good job summarizing the situation.
The Privacy, Security, & OSINT Show – Episode 227