Equal protection under the law would argue that "protected class" doesn't apply. All should be treated equally, yes?Never had one. It's irrelevant anyway. The haters would just have to suck it up and serve Trump supporters. In a same world, where everyone is treated equally under the law.
When political affiliation is a protected class like religion, race and sexual orientation, you might have a point.
Incidently, I've have no problem doing business with someone in a MAGA hat. Money is money.