Seems to me like he said it again (E: or that the spin doctors are telling us about him saying it again now, I doubt it's the first nor the second time he's said something bigoted) because he can see that people are more focused on him using a slur, than they are on the context that it is being used in - excluding gay men from the church.
That isn't to say there's nothing wrong with using a slur, there obviously is and it all feeds back to exclusionary attitudes, but this is clearly a distraction, and it is working very well - I've not seen any comments about the actual discrimination.