Damn, at this point I might vote for a candidate just because he promised not to go on Twitter. But here we go . . .
Were the Tweets racist? Literally no. If you try to read into them, then maybe. It's pretty much in the eye of the reader. Do I care? No. Everything is called racist now, so the term is meaningless at this point. If he wasn't called a racist for this, he'd be called a racist for something else.
Were the Tweets massively stupid? Yes. They were factually wrong (except with respect to Omar), so he looked dumb to pretty much anybody who isn't a kneejerk Trump partisan. In addition, he shifted the narrative in a politically foolish way. A few days ago, the focus was on AOC and her wingnut chief of staff in a pissing match with Pelosi and moderate Democrats. The more often they clash the better it is for the GOP and Trump because it illustrates their nuttiness and fosters division in the Democratic ranks. By posting those idiotic Tweets, he unified Democrats and gave Pelosi and AOC a way to disengage from their pissing match.