People who say “race isn’t real” do so because they are so unbelievably lazy that they are prepared to just spout a manifestly silly slogan rather than do the work of explaining what racists get wrong. They do this even though that silly slogan flies in the face of what their intended audience sees as “common sense”, and so is less rather than more likely to change anyone’s mind; and in fact it just serves to reinforce their previous ideas and to extend their rejection of “wokeism” in any progressive position.
The attempt to dress this laziness up in “scientific” clothes by an appeal to authority based on the fact that modern biologists and population geneticists rarely use the term (mainly due to its socio-political baggage rather than due to any problem in giving it a “scientific” definition) just adds to the harm done because it undermines the credibility of science in general.