Whichever candidate one supports is their own business, and nobody should be attacked for it.
If Mike had posed with a pic of KKK Imperial Wizard David Duke when Duke ran for president (and took the additional step of proudly posting the pic on social media, had it existed back then), would this be an exception to the rule? You'd take issue with a person of color attacking Mike for posing with Duke? What if that person was Blondie?
Not trying to veer into sandbox territory, but just pointing out that some candidates are THAT divisive, and there's a reason why there's so much opposition to the very idea of the band playing for Trump. There's a reason why it's BAD for the brand. I'm not equating Duke and Trump, but I still would like to know your answer to the question.
In the hypothetical situation that Mike would've been photographed next to D. Duke, it's one thing to criticize his choice of candidate. I wouldn't have a problem with that. But, if one attacked Mike as a person, I would have a problem with it. And that's because you don't know why somebody chooses their candidate. Say, Duke had a specific policy that Mike agreed with that had nothing to do with his associate with the KKK.
If a person of color was DEEPLY offended by the association with Duke, let's just say because of the fact that they might have had to use colored bathrooms earlier in life, or continue to deal with many other horrors of discrimination, I think it's fair to say that the offended person has no such obligation to avoid attacking a celeb personally for associating with Duke.
An unapologetic KKK Imperial Wizard who might hypothetically "happen" to have some policy view on a random subject which was agreeable would not just garner a free pass for gaining celeb soft endorsements. Their ugly views would trump (pun not intended) all else, and for good reason. Strom Thurmond might have had a good policy on noise ordinances past 10pm; that doesn't mean that someone who poses with him wouldn't rightfully be shamed.
We'll have to agree to disagree on this one.
And you're kinda getting away from the initial point of people getting attacked for supporting Trump.