What I don't get about this one is that the author, Christopher, put the email server on a Digital Ocean VPS. If I'm not mistaken, DO is a US company and the gov can probably get access to the server's contents as easily as to a Gmail account.
Of course, if Christopher uses PGP for everything, then the gov would still have to find a way to decrypt stuff. But PGP doesn't seem to be commonly used (yet).
I used to have a Gmail account too but switched to Fastmail about 16 months ago and recently renewed my account for 3 more years. It's reliable and the web client is crazy fast.