While I don't endorse his decision, I suspect it might be motivated by a desire to preserve his own public standing. In the eyes of the public, admission that the courts will probably find against you is likely to be seen as effectively admitting one's guilt. Innocent people stay and uphold their reputations.
Today an Italian court has declared that Amanda Knox is, once again, guilty. She did not attend that trial (is not required to in Italy), so her final verdict will be either by appeal to the Supreme Court of Italy or the US extradition court. Extradition requests might be impeded due to the fact US does not have double jeopardy.
Previously on LessWrong, in The Amanda Knox Test: How an Hour on the Internet Beats a Year in the Courtroom there was some complaint that it actually took more than an hour on the internet to thoroughly research the case. Of course, the courts have been at this since 2007...
Her co-defendant, Raffaele Sollecito, who did show up at the trial, got sentenced to 25 years, but I don't know for sure where he is now because apparently he's totally unimportant and who cares (the media's opinion, not mine). I'm fairly sure he's in Italy though. So far it seems the plan is to revoke his passport but not arrest him.
Anyone want to take their hand at making predictions?