In my not so humble opinion: In a free society, it is totally ok to vote with one's pocketbook. If an individual prefers to not shop at an establishment for any reason, it is that individual's right.
And also in my not so humble opinion: Remember the old "No shoes, no shirt, no service"? It is also totally ok for a private establishment to request proper attire - if it is made clear to all before entering that establishment and is handled fairly. I once worked at a restaurant that required suit jackets for men. If they didn't have one, we supplied one. I think it was a navy colored polyester thing. I didn't work there long, but that's another story!
What do you think? Your voice counts!