Should Patrick Kennedy resign?

Orthogonal at DailyKos says so. "The Democratic Party needs to show it's different, that it's not a club of the elite taking care of the elite." The idea is that Kennedy should quit for the good of the party. Memeorandum collects links to Orthogonal's post. Lots of Democrats -- unsurprisingly -- disagree. Aside from what is good for his party, shouldn't Kennedy resign out of simple unfitness to serve?