It's a tough call, it really has nothing to do with point of ejaculation as to an indication, but rather his feelings as he imagined this scenario. It's not even particularly that IT WAS A MAN HE WAS JACKING OFF TO that's the problem. See, even though HE WAS JACKING OFF TO A MAN that doesn't really say he has gay tendencies of any kind.
We really have to think about a few things here, like;
What was he thinking as he was MASTURBATING TO A FAGOT, was he aroused AT THE SMELL OF SEAMAN FAGOTRY or because it was a new experience to him, and this is what was exciting?
If he was aroused by the homosexual scene, could it be just the excitement of the moment, or transference because he was previously aroused thinking of a woman before hand?
The line between straight and homosexual in my eyes is a slim one, I feel all people will have at least some type of gay experience in their life, whether it's simply checking out the same sex as yourself being intrigued, or TOUCHING YOUR FUCKING PENIS WHILE THINKING OF A FAGOT BLOWING OFF ANOTHER GUY. Either way I don't think this is anything to be ashamed of.
Whether it was a gay experience or not is up to him, it is something he has to explore.