There's only one little problem with the idea of a Trible and a Puffskin being the same critter. That being that Puffkins can fly whereas Tribles don't. Now with Harry being 270 years in the future, why is he even worried about not outing the wizarding world? How does he even know if they're even still around? After all, nukes don't care if you're a wizard or a muggle when the explode. And depending on the yield of the warhead, how much area they destroy or just leave unlivable. If you want a real scare, think of this. Einstein published a paper on the Unified Field Theory or something like it. After somethings were said about its' possible usage in war, he pulled it back saying it was wrong in someway. Therefor if E=MC2 lead to the atom bomb, what could the Unified Field theory lead to? And who's to say no government experimented with it? Do you really think they'd tell us poor little sheeple what they found out if they did?