i obviously don't have kids, so my opinion may not be quite what you're looking for, but i don't see anything you did as going too far.
having grown up in a military household, what your son has been punished with sounds like a walk in the park, quite frankly
if he's been giving you trouble and not listening and not eating his dinner, what you've said you've done here sounds just about right. it's enough punishment to knock some sense into him for the moment, but not enough to be the terrible, far too overbearing, disciplinarian father figure.
authority figures aren't going to go away as he gets older -- so he may as well learn to follow the rules now, or you're going to be in for a long haul of miserable parent-teacher conferences in the next ten years. not to mention respecting authority goes a long way in the workplace as well -- doesn't mean being a pushover, but knowing who's running the show is a huge lesson to learn and you've got to teach him that or he won't ever know until it's too late.
not sure if that helps you feel any better or not.