When you qualify for a program and receive your allotment, it is now YOUR money, you earned it by qualifying, and no, taxpayers like you have no constitutional justification within the Social Security Act of FDR to have any "say" in what food you buy with food stamps. Food is a personal choice. Maybe a way can be thought to help encourage better eating by some other agency or method, but what you are describing is just pure fascism. I've said that about 50 times now and am sick of repeating it. I thought this would be plainly obvious to anyone who wasn't a rabid marxist, but apparently not.
It might be different if it actually saved the program any money but it doesn't even do that. There is absolutely no legal nor medical basis in telling people falling into the SNAP program: "Ahha! Now that we have you, we are going to make you only eat wheat germ and celery juice!" That would be like the DOT telling you that since you use the public roads, that the state has the right to force you to only own and drive some two-seater shitcan egg beater little EV.
Maybe dooshbags like you are eager to turn over the few liberties we still have left in this country but I am not. The government already has taken over my medical insurance, banking, and so many other things, I don't need them now telling me what I am hungry for and can buy at the grocery store. No matter what a person buys, your SNAP allotment remains the same.