The worst part is if they are insolvent they just spend god knows how much of depositors money on that domain name.
You're forgetting Mark's arrogance/ego. He would have absolutely assumed that someone would want to buy MtGox out (as if, given that they're knee-deep in legal shit for the foreseeable future) or that the heavyweights of the community would put together a rescue package.
It's likely inconceivable to Mark that nobody regards the "mighty MtGox" as worth rescuing and that "community heavyweights" are distancing themselves from him and MtGox as fast as possible. That MtGox is not going to be given "one more chance" is probably inconceivable to him.
How many times have you seen this before in business - an owner hanging on and hoping for miracles long past the point where it's become apparent to others that it's past the point of redemption? Such behaviour almost inevitably makes things worse for creditors, but it's far from uncommon.