I think that there is a very important point being made in that article by a political science and Afro-American studies professor, that this is not the same thing as the Charlottesville comments:

The public response to Trump’s statements appeared to be a little better for him than in 2017, after the president said there were “very fine people” on both sides of a deadly white nationalist rally in Charlottesville, Virginia.

In that instance, Trump’s net approval dropped by about 10 points a week after the Charlottesville rally.

This time, while Democrats and some independents may see clear signs of racial intolerance woven throughout Trump’s tweets, Republicans are hearing a different message, said Vincent Hutchings, a political science and African-American studies professor at the University of Michigan.

“To Republicans, Trump is simply saying: ‘Hey, if you don’t like America, you can leave,” Hutchings said. “That is not at all controversial. If you already support Trump, then it’s very easy to interpret his comments that way.”

By criticizing liberal members of the House, Trump is “doing exactly what Republicans want him to do,” Hutchings said. “He’s taking on groups that they oppose.”

As distasteful as some might find it,  what he is hitting on here with approval, it is very close to the "America love it or leave it" classic culture wars thing that has usually hurt Dems for decades.  Probably Trump doesn't have the finessing skills to always know where to draw the line, though, and this time he just lucked out.

But plenty of people in the middling areas between left and right get real tired real quick at hearing far lefties constantly talking so much about problems that it ends up that their criticism is read as: this is a horrible country. There is a lot of wisdom in the advice to keep things positive, i.e., we can do better.

Basically I am talking about the 1968 syndrome, where rioting in rage at the Dem convention ended up getting: President Nixon. You can give off that some things are horrible (i.e., concentration camps at the border), but if you start getting the label, fairly or unfairly, of believing everything in this country is horrible and everything must change, then you're going to lose possible votes you might have had. And if you think you are getting the label unfairly, I happen think: tough shit, you should have better marketing, there's always a way to say things better.