Political speech is the most protected form of speech. A ban allowing a Russian or Saudi flag but not a Pride flag is unlikely to pass any constitutional muster. A complete flag ban might be able to, though it would still be awful.
But now we also know that Hamtramck near Detroit is a place full of people who do not want LGBTQ+ people to exist in public. Hamtramck, Michigan. A place full of bigots. Proudly bigotted. It's even part of their official Wikipedia identity now. Good for them, letting the world know their true colors.