It doesn't offer dining plan for kids under 3 so they say they allow them to eat free off your plate. If you look up the dining plan on their site, it will show that.
Another poster on a separate thread ran into some trouble and was charged for his 2yr old. They weren't suppose to charge since he didn't order a separate meal for the child. I don't know how it turned out as it just happened. But I know Disney was wrong in doing so based on what the OP said happened.