But fastmail is based in Australia, which means they can't be trusted for privacy/encryption following the The Assistance and Access Act/Anti-Encryption act.
This. Get over it. Your email is not private or anonymous and never will be. Once you accept that, ProtonMail's value proposition is meaningless. ProtonMail must answer to subpoenas by handing over stored emails and IP addresses, just like everyone else. Here's one example: