Everyone has different tastes and likes different things. To assume that a child is just being an unappreciative brat because he doesn't want to eat something is ridiculous. I'm sure the child's attitude had something to do with this punishment, but the proper reaction to being offered something you don't like is something parents have to teach a child. You can't automatically expect them to know how to be polite.
The other night DH made gnocchi with Alfredo sauce for the kids and with red sauce for me. If he would have tried to force me to eat anything creamy, it would have been a repeat of what happened when I was five and my mother forced me to eat creamed potatoes. They came right back up.
To me, this "You will eat everything on your plate or else" attitude is all about the power adults get from controlling a small child. Very sad. Poor kid.