"What prevents your domain name registrar from shutting you down arbitrarily?"

I did say "even with the events of last week". It's the biggest stick you can get right now. It doesn't make you invincible.

"If you mean your own server on a Comcast line, then your IP is leaked to everyone you email, which is also a privacy hole since it ties your IP directly to your identity."

I don't email out much. Everyone I email is pretty much already going to know I'm me. Comcast already has arbitrarily large amounts of surveillance they can perform on me, sitting here worrying about my "outbound email hole" is a waste of time.