Well... isn't he a friend too? I see nothing wrong with it. Sometimes I think the word boyfriend sounds weird for a grown woman to use. I use it but it depends on the situation. Maybe your husband just doesn't want to spend all the time at the event explaining the relationship, to any people there who don't know already. You don't have to hide all contact or affectionate gestures with him just because you intro him as friend. Or does hubs want that to be suppressed, too?
However, I think it might be your boyfriend's call. Ask him how he wants to be introduced and then see if that's okay with hubs. All three of you can surely come up with a compromise that everyone's happy with.
On the other hand, hubs might be making more of a big deal out of it than needed. I know TruckerPete recently posted about bringing both her bf and husband to a work event and no one raised an eyebrow.