It's not your job to put the wrongs of the world right, but then on the other hand, when and where will it ever stop? What will you say to your kids when they start to have serious relationships - will you be warning them off someone they like because it will cause problems with their grandad? Most people would be horrifed to think of themselves doing that - you too, I'm sure!
He's paid you the compliment of replying nicely - go with it for now, and IF it develops into anyhting serious you can cross that bridge when it lies in front of you. In the meantime, I don't think it's your dad's business to know who you are meeting in a lighthearted dating kind of way.
Otherwise, you might as well be racist yourself, because you actions are being dictated by your dad's sensibilities, iyswim.
And DP was very apprehensive about telling his parents about me - I am not what they thought they wanted as a DIL in many ways related to race and culture. In the end he wrote them a very long letter right from his heart, telling them what he wanted in the world, how much he loved them and how he wanted them to trust him to find someone that he could make a family with. And they did a completeU turn against everything they had ever spouted.
people often behave differnt;y in practice to what they say they believe.
But not always, of course!!