I wouldn't make him eat it personally. My rule is: I make it, I serve it, you choose whether you will eat it. Each snack has two food groups and each snack has a protein, a carb and a veg/fruit. That usually allows enough choice that if someone doesn't like one thing, at least they won't starve.
I do enforce the rule that you must finish your plate before you have seconds, or dessert (which we don't usually have at lunch anyway). Otherwise everyone eats just the noodles, and doesn't touch the meatballs or the veggies. Not fair. That is also the reason that I will dish up the kids plates, as well.
I would keep offering it... what do they say, sometimes it takes 6 or 8 exposures to a new food before a child will decide they like it? But I have told parents that I will not "force" their child to eat something. Man alive; I don't get paid enough to deal with that kind of anxiety (mine or the child's!).