D.P.
At first I thought this was about your husband eating less variety than your child--which is SO MUCH the case in our house. Our son eats everything, husband--not so much. :)
Anyway, I was "that" kid once. Sitting and sitting. The main sticking points for me were brussels sprouts, lima beans, liver, peppers and onions.
Guess what? I'm 47 and STILL hate all of those things! My husband had similar experience with the "sit there til you eat it" approach.
So it's not really an issue for us. If my son hates something (a rare occurrence) he can just NOT eat that part of the meal.
He's 8 now, and truthfully, I can only name about two foods he DOESN'T eat. He was eating steamed mussels at the beach last year!
I think this is largely due to the fact that we've never made an issue out of eating, never 'made' him eat anything, always encouraged trying new stuff, etc.
Maybe it IS your husband's way of "peeing around his fatherly territory" since he's gone so much.
Maybe ask him: "Is this how you want your son to remember dinners with you, considering they are so rare?"
Would he agree to a "try O. decent bite and if you don't like it, you don't have to eat it" philosophy?