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.
1. Inconvenience current users 2. Prevent new users so the service doesn’t gain traction
With the second reason being their true motive.
Hosting locations matter when you are buying network-delivered services. Even if it is trivial to bypass for the user, this one time, jurisdictional risk to the provider is something that you have to consider as a factor when comparing competitors and self-host options.
and when a lot of people are talking about 'self-hosting' they're mostly talking about a VPS they rent from some provider who could vanish just as easily as Proton can. I'd like to see the numbers on how many self-hosting evangelists (I don't mean that term pejoratively. I think self-hosting is great) are actually talking about metal they physically control.
If I don't "self-host", then neither does the corp I work for, with hundreds of machines in other people's DCs...
Everyone has different threat models and resources.
Additionally, if you're on a business plan then you can get a dedicated IP from your ISP or just host in a data center.