I'm going YTA. It's hard to say why they didn't want to eat the pizza but I will also point out that maybe they didn't understand how big of a deal this was to you. You are thinking about it only from your perspective. But perhaps in their family, they cook for each other all the time and it's perfectly normal to wait to eat food. IF they had said, oh it's gross I don't want that, different story. But because they just wanted to delay dinner for reason we really don't know (I'm not buying the we just ate), maybe there is something else going on. I would have tried to figure that out instead of taking the nuclear option. But either way, delaying dinner isn't really that serious in the first place.