There's a certain level of ignorance that is inexcusable in these kinds of matters.
If he had lived in a cave his whole life with no connections to the outside, and then someone handed him a jar and told him to black his face up, then yeah, I can accept ignorance as an excuse.
I can understand him not having a clue on blackface's history. But at a minimum, he should be expected to know by his age that race is a sensitive issue. So when he goes to buy or put on something race/religiously/culturally-related (be it blackface, a bindi, a turban etc.), then he should at least find out whether it's acceptable to do so. And it isn't as if it takes a lot of effort either; it's a very quick "can i wear blackface" google search.
It's not outright hateful racism, but it's a level of ignorance that isn't acceptable. Whether you call it racist or not (I would) doesn't really matter; it's an insensitivity towards race (IMO, this is what makes it racist), and it's a problem.
Although I'm more concerned about the people excusing what he did on here, at this point. :huh: