From the BYU mission Statement:
All students at BYU should be taught the truths of the gospel of Jesus Christ. Any education is inadequate which does not emphasize that His is the only name given under heaven whereby mankind can be saved. Certainly all relationships within the BYU community should reflect devout love of God and a loving, genuine concern for the welfare of our neighbor.
Under this belief, if someone leaves the LDS church, there is the implicit belief within the church and university itself that somehow the mission statement failed that individual because they were not "taught the truths of the gospel of Jesus Christ." There was a breakdown somewhere in which the mission statement of the university was violated. And the university does still operate under the assumption that the LDS Gospel is the truth. Strange, a religion or religious entity operating under the assumption that the faith is true, I know, but its not like people behave like their assumptions are correct either.
Does it suck for people who have a change of heart, who find their beliefs going in different directions? Sure, yep, I'll agree with you completely there. But sometimes change is really painful. I left BYU in 2004 when I realized I didn't believe in the church. I didn't want to stay, I couldn't live with the conflict of interests. I found another university, and jobs outside. I did come back to BYU, about 6 months after I rejoined the LDS church. I reapplied and everything. Is it inconvenient? Sure. But so was giving up coffee, tea, and alcohol when I joined the LDS faith. So would be the case with pastors of other faiths who join the LDS faith.
Every big change takes some amount of discomfort. I don't want a weak and meaningless life where nothing of consequence ever happens because nothing I do has a consequence. Sometimes the consequences suck, but you suck it up and pay the toll because life isn't catered to your special snowflake lives. Life is painful, difficult and full of annoying people you have to get along with. Demanding that the world change because you're too sensitive to deal with the reality that not everyone is like you is stupid. I don't fit in at BYU myself a lot of the time. I don't go around wanting all the missionary-style hair cut kids change to fit me. I don't insist that I be given special treatment because of this thing or that. It comes up, it sucks, but I'm a grown man, and I don't need to get my way to feel satisfied.