Look, if the guy didn't quit then how would that change YOUR team? It wouldn't. I don't see why it should be any different just because the guy did quit.
I think a redraft would be unfair. Some are going to make out better than others in the draft. Adding an extra utility spot would be changing the rules while you are midway through the season.
Sure it sucks to have a quitter, but as mentioned earlier, just have the commish play the guy's best possible lineup. It will still be like having an owner, just a very inactive one.
I had two quitters in my league last year, and sure it sucked, cuz they had some guys that I was looking to trade for. But at least if I wasn't going to get those guys, then no one else was, which is very fair.