Meaning he would be okay with it but, at least initially, he would be unbearable. He gets that way a lot. For example, he hates the color of my sisters hair right now (she dyed it pink for Otakon). I think he could live with it, but he's adamant that she dyes it to a more natural color before she starts teaching undergrads next semester.
I've been watching his reaction when any issues that have some sort of gay component come up and I'm getting mixed signals. When Gov. McGreevey resigned for "lying to New Jersey" by appearing to be straight with a classic American family, my dad said that being gay was no reason for him to resign, rather his piss poor administration was the real reason (New Jersey has a bad track record with Governors). However he has yet to give a clear opinion on solidly gay issues, such as same-sex marriage. He is also not above making jokes, as he has done that as least twice that I know of, but it was mostly a reference to the feminine kind of gay person (which I am not).
Anyway, I get the feeling that while he would accept it, he certainly wouldn't introduce me as his gay son (as he shouldn't) in the sense that he would be proud of it. On the contrary he probably would not be proud of the fact that I am gay. I could probably bring a guy home to introduce to my parents, but I don't think we would talk about it.
At least, that's how I construe it and imagine it.