Many public places already have massive signs like this. Whether they're enforceable I have no idea, but the comparison is not direct because an owner of a business has the right to kick you out for almost any reason (there are exceptions for non-discrimination, of course).
Every time I have seen one of those signs, it has contained provisions to describe manners, dress, or behavior common in poor people or minorities; it seems to me a way to codify and formalize discrimination against those groups.
