Maybe those types aren't motivated by their politics first and foremost.
Maybe they want to move on, live their lives and be left alone by the ivory tower technocratic know-it-alls of academe.
So you're saying they don't believe in the value their beliefs and profession as highly, and have other motivations?
Then that's a problem for Conservatives, and there are ways you could support, right now at this moment, Conservative teachers who DO value their political beliefs and profession high enough to stick it out.
I'm not being snarky, but I think you're probably closer to explaining why Professors are leftist than the OP. The Leftists simply belive in their jobs and political beliefs more and are therefore more willing to stick out crappy pay and crappy hours.
I know I could leave my job for an 8 to 5 job and make a LOT more money. But I like my job and think its important. So I stick it out.