I think he's responding to the line "harder sciences are proving that social sciences obsession with identity politics has hindered medical advancements" which

I think he's responding to the line "harder sciences are proving that social sciences obsession with identity politics has hindered medical advancements" which I would consider false. The existence of genetic diseases that are largely present in a single race has been known for a long time. Tay-Sachs is seen almost entirely in Ashkenazi Jews, Sickle Cell is mostly seen in Africans, etc. I don't think "identity politics" is rejecting this notion, or if it is it's doing a bad job of it.