@ Tristan re: "What happened to "innocent until proven guilty?" Please note I already said "This particular case is perhaps not so clear cut"
@ Markus re: "How do you know a exit server is compromised?" You don't always know. With any skill on the attacker's part, you will NOT know. Still, sometimes attackers do stupid things, like run sslstrip, otherwise try to man-in-the-middle SSL, etc.
As I already said, this particular case is not so clear cut. However letting the police poke around on the hardware is a really good reason not to trust it! I mean, I'd personally burn it all down and start over. Looks like that's what the Seattle operators are already doing, so this is perhaps a moot discussion.