I agree with you 100%. It’s entirely okay for a professor to hold a viewpoint on any given issue, as long as they are transparent and allow for honest debate. I, unfortunately, did not encounter much debate or free thought in my college experience (Cornell, where I majored in Entrepeneurship). I often felt that I needed to tailor my essays to fall in line with my professors’ viewpoints, and didn’t feel there was much (if any) room for debate on basic left/right issues. I encountered this problem in a wide array of topics, ranging from Economics, to Sociology, to History, to even a few science courses.
And as to your example of an educator discussing Trump, I think the problem has become that the ONLY possible viewpoint is “I dislike Trump”. The range of acceptable opinions seems to be limited to that basic idea, with varying amounts of explanation offered. However, I can’t imagine what would happen if a professor at any University or college openly stated that they “like Trump, and here is why”. Would there be protests? Would that professor encounter issues with their peers / the administration? I’m not even an outright supporter of Trump, but to cast him and his supporters as simply incorrect/evil/stupid is dangerous. Opposing viewpoints need to be critically analyzed and discussed, not simply treated as incorrect and thus ignored.