Seems to me it's the other way around. Liberalism was born in academia and has spread from there.
What is it about people with MA and PhD programs that fosters a liberal environment? Your answer just reinforces the question OP asked.
There more education I've received (high school, BA, then MA, now MA+45) the more liberal I've become (mostly on social issues I'm more moderate on fiscal issues). And I was raised in a fiercely conservative family with conservative grandparents.
So, there is something to this!
Oh, and many of my teachers were also conservative (religious private schools for BA and some MA), but I still ended up more liberal.