Well, people are really commenting on this one, on how there is no easy solution, and it was just unrealistic to expect everyone to stand down in one second like that. At least, in "Day of the Doctor," I think all of the Zygons were there for the negotiations, because there weren't that many. I'm still not quite sure how a few Zygons suddenly became 20 million (was that the right number?). Did they have lots of little Zygons, or were there that many who survived the destruction of their world in the Time Wars? There are a lot of questions on this...