Then users will swarm the boards wondering why their transactions went through. The community will discover they've been attacked, and will roll back / fork the network to vote in a new set of delegates. The attackers attack will have been for naught. Short term, this attack will give BitShares a minor black eye, but long term it will show how resilient the network is and there will be no more incentives to perform this attack again.
This won't work for DACs. They can't read forums. A good solution ought to be automatic.
Already addressed by a previous post:
"BitShares always has a back up plan in case of the unpredictable black swan, but it doesn't waste time squabbling about optimizing the effectiveness of plans that are unlikely to ever be needed."
"Its why we will make the money while those chasing perfection will end up teaching university courses. "
You opinion of what is a 'good' solution is just your opinion, based on a theoretical assumption that a DAC can't have human intervention. As a practical solution, I think my solution is great, and it kills the incentive for such an EXTREMELY improbable attack.