Quite a good read.
In many ways he is correct. Liberals have forgotten how to speak with (ot to or at) rural and working people. Thelast one that I remember who saw that and really appealed to both urban and rural, educated and working class was Bobby Kennedy. He would have won in 1968 had he not bee shot.
The basic point is the divide is racial in that it stemmed from Civil Rights Bill 1964. Until that point that South went Democratic. In 1968 there was a 3rd party candidate, George Wallace governor of Alabama who split the vote but not enough to stop Nixon. 1972 it was all over. The South is solid GOP and will be for years.