rational: Why is the profit (minimal) of the store inherently preferable to the expense (maximal) of your friend?
It may be more important to help the store than an individual poor buyer:
1) you want to help someone in business NOT to become poor in the first place
2) the store is in the business of helping multiple poor people, they will be worse without the store, especially after federal assistance will end
3) you would like to encourage local residents to go into business, like the store owner, rather than collect free federal food. Current system seems to provide more incentives for the latter than the former (although, I presume the store also got their PPP loan)