I think it is more than the "spilling of seed" that gives some hetero guys the willies when they think about gay guys. I think it is a deep-seated (as in anthropological, from the pre-evolution times) need for the male of the species to attempt to show dominance, like trying to be the alpha dog. Almost all species, the males compete to be the biggest strongest and to get to procreate with the females. To not be the dominant one means to be submissive and roll over for the big guy. That in human terms could be viewed as "shameful", or repugnant. No guy wants to be the one who runs off with his tail between his legs in a dominance contest. I think many straight guys can't imagine being gay because it means giving up that dominance, and that also explains why many straight guys would say " I'm not gay, but if I had to put in that position (long prison term for instance) I'd definitely be pitching and not catching."
I totally respect celebrities that keep their private lives private. If they live away from Hollyweird, most people hardly look twice at celebrities, and just treat them like the normal people they are.