Him having had a lightning talk at DEFCON, having attended conferences like CCC, having many prior dealings with law enforcement thanks to his email service and many people of interest using his service might have something to do with it.
I highly recommend having a look at the transparency page, it includes audio recordings of phone conversations with the FBI and more. Fascinating stuff if you are interested in how law enforcement works. For example, handling an NDA request [1].
E: The transparency page might be of interest to you: https://cock.li/transparency/
Or possibly you'd want to hear about the time the servers got seized: https://news.ycombinator.com/item?id=10774152 && https://news.ycombinator.com/item?id=10912524