if that opinion is racist then yes.
The often mooted argument that 'we are against politics' doesn't really wash because no one boos at the NHS being supported, or at the poppy appeal, or any of the other things that are related to bettering society. It's only racial equality gestures that seems to come in for this criticism, which can only lead to one conclusion.
What next boo Marcus Rashford for daring to make sure kids don't go hungry, because you know that's "politics" stand outside a foodbank and boo anyone donating food? It's nonsense. People used to say "everything is politics", and it's true, I think what the booers actually mean is "this is party politics" this is left vs right, and that makes this about the demonisation of anything that shows empathy as being far left. It isn't though, human decency shouldn't be related to how much you think we should get taxed, or what form of governance we have. You can be on the right but not racist, so what this appears to be is a growing far right, extremism where empathy disappears and is replaced by hatred.
Anyway, BLM, knee taking, if you don't agree with the gesture ignore it, if you boo you are a part of the racist problem, it's pretty simple.