Pretty much, but that isn’t the idea behind this block. Someone used ProtonMail to send a lot of different bomb threats to the police. Because of this block police now have some legal ground to ignore those threats.
It seems all evidence is based on the emails sent by the author of the bomb threats. I don't think it works as evidence against this being an inside job.
Agreed that it’s not possible to know for sure what’s going on. But it’s not the first time this kind of stuff happens however it’s the first time action was taken.