Expulsion of gay student

Well, this is dumb:

Johnson, a sophomore majoring in theater arts, was expelled from the university Thursday because he declared online that he is gay. In a statement released last week, the university's president, Jim Taylor said students are held to a "higher standard" and that "students know the rules before they come to this institution."

Ok, on the face of it: it's a Baptist university. The rulebook says you have to uphold Baptist standards, which apparently means homos are no-no's.
Problem is, the rulebook didn't say that when this guy started college:

But a copy of the student handbook provided by the university confirmed the policy was not spelled out in 2003-04, when Johnson chose to attend. The school did not provide a copy of the policy for the 2004-05 school year. The 2005-06 student handbook says: "Any student who engages in or promotes sexual behavior not consistent with Christian principles (including sex outside marriage and homosexuality) may be suspended or asked to withdraw."

Seriously. He'd been there since 2003. It's a few weeks till the end of the bloody school year. Surely, anyone he was going to lure into his web of sin and infect with evil gay flu was already a lost cause, right?
It's a religious school. It's a religion I'm not particularly fond of, but on the face of it I can respect their right to make their own policies. As long as they're not doing it on me, I couldn't care less.
But this...seems a bit much. The policy wasn't spelled out when the guy enrolled, and for his part the guy wasn't exactly running around campus in a leather vest and ass-less chaps singing "YMCA."
How would it have harmed them to just let this guy pass?