This as a very old chestnut.
Think on this, the campaign for nuclear disarmament wants this country to abandon nuclear weapons, the "reasonable" folk say that's foolish, they prefer multilateral nuclear disarmament, which will never happen, therefore we continue to have nuclear weapons. The multilateral nuclear disarmers, in any practical sense, might as well be pro nuclear for all the good they do, because the end result is we continue to have nuclear weapons. It gets to a point where pro nuclear folk and multilateral disarmers are, to all extents and purposes indistinguishable, because despite their differences the outcome is the same.
Discrimination exists, you accept that. If we discount rich white blokes, I'm sure you and I can think of any number of groups with a legitimate axe to grind. What I cannot think of is any discriminated group that has not had to engage in some form of protest to get what they want and I struggle to think of any group that succeeded by widening their grievance net to encompass every downtrodden group in society. In fact those that oppose the aims of a particular discriminated group deliberately widen the grievance pot to confuse the issue to ensure nothing gets done. So Black Lives Matter becomes All Lives Matter, the motives of the movement are questioned, us and them lines drawn, culture wars stoked and no brainer basic assumptions questioned. Initial sympathy begins to slowly drain away, momentum lost and the issue fizzles out, usually with a prolonged enquiry, delivered quietly long after the fire has burned out.
So with all this distrust and noises off, it's important to see things for what they are.
The BLM movement has exposed two major players. Racists in our society who want racist and discriminatory practices to continue. And reasonable, predominately white folk, who don't consider themselves racist and do not display racism in their daily lives, but feel uneasy about BLM and their motives. These reasonable folk feel uncomfortable about some of the changes that BLM are demanding, they question the assumptions that BLM are making and suspect this might end up as a zero sum game, with them losing out.
So these reasonable non racist folk muddy the waters, obfuscate, engage in whataboutery, all with the best intentions you understand, and just like the multilateral nuclear disarmers being indistinguishable, in any practical sense, from the pro nuclear crowd, the non racist reasonable folk might as well be Tommy Robinson for all the good they do, because nothing changes.