Yes, I think it is unreasonable. May I ask why they are uncomfortable with the situation? They must feel he is gay or some weirdo, or else why would they object to his decision? In which case if they think that then they are very shallow.
One of the other players objected to us having to roleplay a scene which involved the female character being romantically linked to a male NPC. While most of the interaction was discussed one on one with the player a bit of it was done in general session as well. Two players grumbled about it but one was particularly objectionable. He e-mailed me with the next day and said it was not what he wanted from the game, that the session made him feel uncomfortable and he wanted it to stop.
I spoke to the player in question and he said he was feeling uncomfortable as well. While he had expected a few jibes here and there, he was not impressed with some of the comments made around the table. He actually felt embarassed, like he had done something wrong. I didn't mention my e-mail discussion as I didn't want to make him feel even more disheartened.