They "like" him because he teaches to the test instead of imparting knowledge. He also makes it known what views will incur his wrath, so better grades are more easily acquired.
Going back to a little over 40 years ago when I was in college, I think I would have been able to hold my nose about his politics and enjoy his teaching. It was always nice to have a professor predictably teach what he was going to test on and “teaching to the test” that way definitely was not a failure to “impart knowledge.” Rather, it imparted the knowledge that as to be tested on, certainly a lot fairer than conveying a cloud of BS and expecting the students to guess what was important and to be tested on.