This also should help resolve the question of whether Trump’s antics are sincere or calculated: The answer is both. Trump is as dumb as a sack full of rocks, but he understands that racism gets his base excited because it gets him excited. If anything, his incuriosity and stupidity are an asset when it comes to connecting with his base. Clever people might overthink this — Trump just goes out and says the vile, empty crap he’d want to hear. It generally works.
Obviously, Trump has other tactics besides racism exploits to occupy his base’s attention so that they don’t have time to think about whether they really want a corrupt president who seems beholden to a Russian dictator. Churning up hatred of ambitious, smart women is always a good bet too, as evidenced by Trump’s Thursday night speech in West Virginia in front of a bunch of whooping jackasses chanting “Lock her up.” He also straight-up asks his followers to ignore the Russia story, as with his announcement that there “were no Russians in our campaign” in that same speech.
This is crude strategy, but it could be effective. Not the part where Trump gets defensive about Russia, of course — that just serves to remind people that he’s worried about the investigation. But for two years now, Trump has been able to get his supporters to forgive him pretty much everything as long as he keeps sticking it to people they hate, from liberals to feminists to people of color.