So why is it OK then for an establishment to fire a person solely for supporting Donald Trump on his own time, but not BLM?
Not all people, organizations or political ideologies are equal and they should not all be treated equally. Being anti-democracy is not the same as being anti-socialist and should not be treated as such. Supporting minority rights is not the same as supporting neo-nazis and should not be treated as such. For the record, I do not FIRMLY believe that it should be illegal to fire people for supporting BLM. From a moral perspective I think it's wrong, but I haven't given enough thought to whether or not it should be illegal or not.
BLM is, after all, a political organization with views many would consider extreme.
You have been told 100 times that 99% or more of BLM protestors were not officially associated with the organization known as BLM. You and others like you have also provided ZERO evidence that the statement I just made is wrong. You continue to repeat this talking point, even though people have pointed out 100 times that it isn't true, and you have never been able to explain why it actually is true. This means one of two things... either you are operating in bad faith, or you not only believe something with no evidence that it's true, but expect / demand that other people will take it seriously when you use it for part of your arguments in political debates. Not how real life works.