If you listen to the video of what Scott Adams says, he's quite explicit about it. It doesn't seem like a plausible misspeak. He didn't merely say "It's okay to be white" in an ambiguous context (plausibly not related to the 4chan propaganda campaign.) He said that because some poll claims whatever% of black people disagree with the phrase, that black people are a hate group, that white people should stay away from them, and that he would no longer advocate for black interests. If you don't trust my paraphrasing, fair enough, but you can watch the video yourself and I think you'll find that my paraphrasing is fairly accurate.

Suppose for the sake of argument the poll is legitimate, and suppose he wasn't aware that the phrase is a 4chan propaganda slogan.. I think he still grievously erred when he decided to judge all black people by the opinions of only a portion of black people, as though black were a political affiliation that people can enter or leave at will. But it's not a political affiliation, it's an ethnic group. You legitimately can't claim that an entire ethnic group is a "hate group" because whatever% of them believe hateful things, even if that statistic is true. It's not as though the remaining% can disassociate themselves from the ethnic group, it isn't a voluntary association. I think his failure to distinguish an ethnic classification (involuntary association) from an ideological classification (voluntary association) is where he really went off the rails with no plausible deniability.

I interpret this whole affair as: he's rich, wants to retire, and decided now is as good a time as any to finally speak his mind. He lost his inhibitions.