My partner and I have never as of yet experienced homophobia on a cruise, we have met other LGB members also. I would be more concerned about our own community's homophobia on an all gay cruise - and we did one and found we faced more problems because we did not do that "party scence" or "gym bunnies" - we do know homophobia is everywhere
What ever you do you will enjoy your cruise I am sure - and Have Fun and just be Safe.
D & D