It seems most of these ideas are being considered in almost a vacuum.
A relief agency is going to limit how much they distribute. Based on how many cases of water they have and how many people are around. These will exist no matter what the laws on gouging, because there are a substantial amount of people that genuinely want to help those in need.
I know of numerous companies/people/agencies that are sending trucks of supplies to the Houston area from ATL all because of the compassion and generosity of the people. I am sure there are semis heading from all different directions for the same reasons.
Even a rich person with tons of cash cannot pay and get more of these resources. They are distributed as needed based on the situation.
There might be some that are so desperate that they would attack a guy with a pickup truck full of water that was selling it for $20 a case, but most are not going to resort to violence if there is an agency giving it away down the street.
But to get that water, anyone knows they have to stand in line to get whatever the limit is (1 bottle per person, one case per family, etc.). The same rich guy from before has to stand in line with everyone else, but if there is some guy with a pickup truck, maybe that rich guy is going to go to the guy selling for $20 a case and skip the line and hassle, but also freeing up more water for those that do not have the cash. Sure, he could still stand in line to get the free water, but if he has the cash, he will not.
If gouging cut out relief agencies, then of course it would doom the poor to die. But in the real world where both exist, everyone gets what they need and some get more, but no one dies.
As stated before, if a store owner has to sell at normal price, once the stock is gone, it is gone. The store owner has to survive, so how much are they going to hoard themselves knowing that doing so might hurt others, but not keeping the water leaves them without essential supplies.
If resources are that scarce, then keeping said resources for yourself in reasonable supply to ensure your survival is also valid. But if the store owner can raise the price, maybe it is worth selling some additional supplies.
The reality is, anti-gouging laws will not go away because politically it is a bad idea to do so. Anyone suggesting such is going to be raked over the coals for not caring for the poor. Even if such laws cause more harm than good in the situation.