A good response for those rare semi-self-aware cases would then be, "So you're implying that by calling something a racist dogwhistle is in itself actually a racist dogwhistle?" And really screw with their brains that way, and if they take the bait there you can whip out all the anti-white "totally-not-racist" hate. Or continue waffling, either way is funny as it uses their fondness for weaponised pedantry against them.
Label: no hate