You're twisting his criteria into something it's not, but even if we're going to do that, you're still wrong because there were a lot of close States in those presidential elections.
The States he has listed as Republican are, for the most part, naturally GOP; and vice versa for the Democrats. The main one I would disagree with is West Virginia.
In 1972, Nixon won 48 states by at least 6 points, and a 49th point by 5 and change points, while losing 1 state by over 6 points, giving us 97 "natural" GOP senators.
In 1972, the Democrats *gained* in the Senate, ending up with 56 Dems, 42 GOP, and 2 who knows.
In 1984, the Democrats also gained in the Senate, ending up with 47 Dems, 53 GOP.