Even if “people who aren’t vaccinated against COVID” isn’t a protected class? I don’t think this would be an easy type of discrimination case to win, mostly on those grounds.
Edit: on second thought, I imagine “religion” would probably be used as the loophole to get around that. It always is.
Edit 2: I’m not bashing religion at all, I have no issue with believers. I do, however, have an issue with people who use religion as a tool to manipulate people and get what they want. The line of reasoning here would be “I can’t get vaccinated because my religion doesn’t allow it” (blatantly false for most, at least for Christians, but not disputable). “This business won’t serve me because I’m not vaccinated, so they’re discriminating against me on the basis of religion.” So we’ll have a world where businesses can refuse to serve customers because of the owner’s religious beliefs, but other businesses have to serve other customers because of the customer’s “religious beliefs”.