I took that more to indicate his frustration with Vala's continued advances...

and honestly, in canon, while he might be minimalized by those who do not really know him due to his civilian status and the um, glasses (some people are so shallow), they do seem to quickly discover they have underestimated him. I never saw anything in the actual show which would lead me to believe he was being questioned on his sexuality. Does make for fantastic fic tho!!!!!