The activist knew, and Tory probably knew as well, what race the suspects were going to be.
and, as you say, "probably so knowing", Tory chose to use the dehumanizing "sewer rats" label... the broader stereotype triggering "vermin"! So helpful. By the by, has Tory similarly labelled the (alleged) serial killer "body in planters" dude? Wait, he's white... carry on...