But if that plumber was fixing your pipes and going off about the war and GW (opposite your beliefs), do you think you will call that guy back for more work?
that is the point. No I wouldn't. He doesn't think because he is a successful plumber, that he therefore is qualified to mouth off to the world what he thinks about everything. He is afraid of offending his clientelle, so he doesn't do it, because it would hurt his bottom line. Celebrities think they live in a vaccuum where they are special.
Btw, I actually had a professor who I had a talk with in college because I found his political lecturing unbecoming... and I agreed with him for the most part politically. I just asked him why he thought it was appropriate for us to know in Geology class what his views on election 92 were. It was totally out of the scope of what we were learning.
Academics and celebs think they should be immune to behaviour that everybody else finds reasonable.