You seem determined to miss the point; you aren't getting that my point isn't about racism, it's about activism.
I would give this advice to him in person (because I'm not a coward who bites his tongue) and I'm sure many other people, many people who don't share my skin color, would too. You have a simplified binary view on this topic, you're implying that anyone who puts 'end racism' on their helmet is against racism and anyone who doesn't or who opposes that is somehow for racism.
I'd wager that people like MJ, Shaq, Barkley, D.Rose, etc, did more to discourage racism just through their play, than anyone ever managed to accomplish via virtue signaling activism. It's pure cringe that the first black QB in Bears history has to put 'end racism' on his helmet when his forbearers never felt the need to do anything like that. Are you going to try to tell me that MJ supported racism just because he never virtue signaled his opposition to it? Of course not, that's silly. He discouraged more racism just through being MJ.