Well, honestly, what was he expecting? It's one thing to declare, "I'm going to join the Avatar." It's another thing to get him to let you stick around after you've made several months' favorite hobby of trying to bag him like a gopher-rabbit.
All joking aside, I'm so proud of Zuko I could burst (always knew he had it in him), and I can't wait to see how he integrates into the new Gaang Plus. I just...won't be too surprised if this is how it goes at first, you know?
(One week later...
Toph: Argh, is he still there? Can't we just land already?
Sokka: Toph, you know we can't go to ground until we know there are no Fire Nation troops after us. If they find out our hiding place, we're done for!
Teo: Aw, but he's so pathetic!
Zuko: *far in the distance, flailing after them in his little balloon* Pleeeeeeeeeeeeease! Waaaaaaaaait!
Katara: Hmph. You don't know him like we do, Teo. Trust me--he is a master of deceit. *headtoss*
Zuko: ;________;