@Markus
Okay, so you are offended by the phrase "it's that simple". Sorry, if I could remove that sentence I would. I didn't mean to imply that running an exit was trivial or easy.
Otherwise, I stand by my argument -- automated filtering or blocking is not the right answer. The co-founder of Tor already said as much in this thread: "it would seem that using an IPS is fundamentally dangerous for relay operators".