Under federal law, age discrimination can only be claimed if the “victim” is 40 years old or older. And it only involves employment (I think).
https://www.eeoc.gov/laws/types/age.cfm
Maybe there are state laws that might apply here, but I doubt it.
Anyhow, even though I think Wal-Mart is wrong, it’s their store. I don’t see any need to cry discrimination. It’s kinda like the pool hall up the street from me. They’ve got a “No one under 18” sign in their window. It’s their pool hall. Let ‘em make whatever rules they want to.
Yes, the liberty question should rule, I agree. My point is that the system is moving toward forcing businesses to go against their conscience in so many other ways. So why would it be permitted in this case?