CK,

I think you are confusing the laws regarding political campaigns and the FCC regs regarding "equal time".  Basically says that media under their auspices must give equal voices to candidates- air-time wise.  

So far as the 1st amendment, when it comes to "speech", such a scenario in your example, it would not apply to a private insitution.  If the college was a "state" college and you could somehow tie the "censorship" to the state, it would be constitutionally violative.  Otherwise, a private entity can do what it likes with speech posted on their premises.

Free speech guarantees under the 1st amendment and the attendant caselaw only apply to state or federal "governmental" action.

The Constitution and Bill of Rights doesn't apply on University campuses. Just look at their stance on firearms ownership.