BEST was funded by a501(c)(3) called "Novim", to which the largest contributor was Charles G. Koch (via the Charles G. Koch foundation), and I don't think Mr. Koch funds communists.
This was the home team, and IMO it's quite telling that it ended up providing strong support for the "consensus view" of the climate trend over the last hundred years.
Actually the home team players (not Mueller) were not happy with the way the filters were applied. The BEST definition of rural was 10 miles or so from a major city. So that explains why their data showed very little difference. If they applied correct filters, they have to show a significant difference from previous studies. Otherwise the urban heat island effect, which the entire civilized world recognizes, does not exist.