This is true on an individual level. But I think panic buying is not a responsible thing to do, especially when the Government and the Food Industy have told people not to, and certainly not in excess. If everyone tries to hedge their bets and buy up double, triple, or even more food than they actually need, that it how you manufacture a food shortage. Someone mentioned the Fuel Strikes of 2000, and the small potential of minor fuel shortage leading to a huge fuel shortage because of people responding disproportionately to the risk and consuming more of the endagered commodity than necessary.
If you manfacture a food shortage, then you increase the amount of people panic buying and demand further outstrips supply, in a vicious circle.
This is not effective or fair resource allocation.