It's a known issue that unrestricted commerce or indeed unrestricted ANYTHING is unacceptable because its trivial to imagine situations wherein an actor or actors can misuse the situation.

We cannot and shouldn't contemplate a solution to any and all possible feasible problems because time is finite and a solution that in theory results in the best outcome for a..z wherein h..z are hypothetical and a..h are actual may actually be a worse solution for a..g

The analogy is ridiculous on its face. It will never be actual. In such a situation we would trivially resolve it by passing a law that food stores can't blacklist groups of people while retaining the right to blacklist individuals for actual misbehavior. This would be somewhat limiting on the freedom of small shopkeepers to say throw out nazis but it would break the back of the "big food for lower taxes" coalition. Since none such exists this solution is as described above worse for the set of problems we actually have to solve a problem that is only hypothetical.

It would be more productive to discuss the ACTUAL issue by addressing it directly instead of trying to reason by analogy. It's not like its a topic people on this site have trouble understanding. Going off into the weeds like this just wasted time.