No, Trump did this on purpose. The simplest explanation is the most likely.
This I disagree with, particularly since he doesn't have to consciously "know" or acknowledge anything explicitly for him not to understand the basic import of the statement.
I don't think anyone's saying he's capable of giving a brief one paragraph statement for an SAT question concerning Civil Rights activism in mid-20th century Florida, cause biases and prejudices don't need that much formal verification to commerce
He knew what he was saying. But, coward that he is, he’s claiming to not know where the words came from now that a reporter asked him.
I remembered that admittedly tasteless joke because (a) it rhymes and (b) it’s pretty violent and offensive, which makes it somewhat vivid. And honestly, “when the looting starts, the shooting starts” hits the same notes.