It's not tribal to believe that MLK was a preacher, it's what he was after all. I just think that other civil rights activists contributed more to the Civil Rights Movement.
He would probably speak up about it and call him "pregidious, a bigot, a tribal", you name it. MLK was just a preacher.
It's obvious to anyone that the implication here is that you don't think MLK Jr. was important. You're saying that he was
just a preacher, and that all he would do is call Donald Sterling "pregidious[sic], a bigot, a tribal" (with the implication that the guy who doesn't want Black people at his sports games is definitely not tribal).
While disliking MLK alone isn't racism, it's pretty much fool-proof heuristic evidence that you are a tribal.