By saying the question was racist or was a racist question, he was saying that it was the kind of question that only a racist would ask. In other words, it is implicitly a comment on the person asking the question.
BTW, I heard this exchange on the radio and didn't know the race of the person asking it. But now that I know, I would like to say that it was brave of the President to point out that, yes, a person of color can be a racist (even though Liberals insist they can't because they lack institutional power...whatever the hell that means).
“BTW, I heard this exchange on the radio and didn’t know the race of the person asking it.”
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You obviously didn’t catch her name-— Yamiche Alcindor (from PBS).
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Sometimes my children do bad things and I tell them what they did was bad, because I expect better behavior of them. This is very different then simply dismissing them as bad people...even though one is presumably a bad person when one does a bad thing.