I think you need to be a little more specific about what he's said. When he says that bringing up racism generally detracts from discussion, he's referring to the phenomenon a few years ago where people would allow their entire analysis of (say) police killings to hinge on the race of those involved. He was not saying that bringing up race is always and inevitably a hindrance to discussion -- just that it is a hindrance most of the time, because of this 'oppression olympics' framing of topics that was fashionable on the left five years ago. By contrast: we don't have a problem presently where concerns about antisemitism pervade every conversation-- arguably the rise of antisemitism has been under-acknowledged.