This was an intentional attempt to redirect the conversation. Throwing out red meat is a strategy that works every time especially if it has a racist element to it.. Nothing motivates the presidents base more then seeing black people outraged. Trump supporters view it as black people complaining again and demanding white people acquiesce.
It should be mentioned but we should not linger on it.
People need to remain focused.
It is imperative to Trump's base that they feel both Trump and they are UNFAIRLY put upon by anyone not of the base. Trump represents their view of themselves both that he is unfairly treated but simultaneously Yuugely successful through his own efforts that overcome all that is put upon him. That's the key to Trumpism. It's anti-elitist, anti-immigrant and anti-intellectual. At it's base, Trumpism allows people to see whatever missed opportunity they perceive is someone else's fault, but they overcome that through Trump. "Only I can save you."
The racism aspect is simply that he's been blaming Blacks for everything since 1970. LOL
But when he told Pelosi "I'll see you at the polls," he really meant it. You're right that he's just giving his fans red meat. And you're also right that overemphasizing the racism aspect just misses the overall reason for his success with his base.