Which is more dangerous for gay people in the long run, hate speech or a society that bans those it disagrees with?
[I have no problem for the discussion to move it out of the specific of NUIG's action to your broader question.]
I think you're not comparing like with like. Hate speech and something I disagree with are not the same, and neither is the same as harassing speech under the equality legislation.
By coincidence, this week my reading on the bus to work has been an essay by Glen Newy reviewing a book that discusses where the boundaries should be. I think non-subscribers can access it here: http://www.lrb.co.uk/v35/n23/glen-newey/unlike-a-scotch-egg