As a person of color, I always find your reasoning (not the dad's) somewhat ridiculous. The fact is being related to someone who may be impacted by these things does actually change how people behave. My non-POC wife married me, and obviously, she now cares more about issues facing people of color. Not that she didn't care in the past, but now it's not a matter of an abstract idea (which people rarely put themselves out to defend), it's her children and husband.

Cut the guy some slack. It's perfectly natural to prefer those you are family with.