For the record, I think that what Kevin did was completely understandable (buy all the bitcoins he could, for as cheap as he could). I certainly probably would have attempted to do the same, given the opportunity.
This, however, doesn't mean that I think he should get to keep the funds. He got lucky and managed to make off with 600+ bitcoins, but that doesn't change the fact that those bitcoins were stolen. In the real world, if something is stolen and sold to someone else, the stolen item still belongs to its rightful owner and has to be returned if at all possible.
I think that most of the people who are rooting for Kevin are people who made out like bandits when the crash occurred and what they're really wanting is to be able to keep their ill-gotten gains. Kevin is their poster child.
The best solution is to take away the ill-gotten gains from the greedy hordes (an image of Cartman whining about not getting his way springs to mind) and just roll everything back to the way it was. I, for one, would love to see the market return to $17/BTC and for everyone's account balances to just be back to what they were and this whole incident to have effectively never happened. Mt Gox will have to spend a lot of BTC to rewind things and put things back in order. I think that's punishment enough for their security problems.