Family-oriented people get very angry when some 30-year-old girl is passive-aggressive to her racist uncle and offer solution to be tolerant. Yeah that's one way to see it.
My concern is that the racist uncle stings for a minute, but it habituates you to be passive-aggressive that will damage your important relationships for decades. You are actually the loser here, way more than your uncle.
But the real question is, you are already a grown-ass person, what stops you from ignoring your uncle entirely? You don't even have to tell them to get lost. You just ignore them if you don't want to confront them. So why not? They will get bored really quickly.
No, you want to give mixed-signal. A negative signal to satisfy your hate. A positive signal to diffuse the hate and keep the relationship running. Because if it ends officially, you lose an option. An option to say “we are still family” when you need help.