It's wrong, but I think people just disagree with trying to make an equivalency.
It's like if you kick somebody, and they're mad, and then you put your hands in your pockets and start whistling and say, "I don't know why he's mad! Why is he so angry?".. Except on a societal scale.
I don't support any racism. But it's clear that some people are just upset that they're growing up in a society that spent a couple hundred years killing their ancestors, beating them in chains for free labor, assaulting their women, splitting their families up, not allowing them to vote, not allowing them to be romantically interested in someone who didn't look like them, not allowing them decent jobs, etc.
And that people are still allowed to roam the streets with the flags of the failed insurgency that attempted to enshrine slavery forever here, and to push an agenda that they (and immigrants as well) don't belong in this country. Under the banner of 'free speech'.
To compare that to people who are punching down at a group of people that is living daily with the fallout of both past and present racism is absolutely silly, even if neither of them is 'right'. Any more than you wouldn't tell a kid who was abused as a child to "just get over it" and think that that's actually helpful.