At 2 and 4 I would laugh it off. I might have them help me re-wrap some of the gifts. Honestly at that age I wouldn't have even had any under the tree to tempt them. Especially the 2 year old isn't mature enough to with stand an impulse and temptation.
And letting a 2 yo. eat dinner in his/her bedroom is a scary thought.
There's just something ironic about punishment being doled out because, "dangit, kid, I wanted your gift to be a surprise." Um, "little less love, little more common decency," as the song goes.