Gather them all
Everyone had remained at the stadium for a while. There wasn't any trouble happening on their respective planets, so they thought it was safe to stay there for the time being. Everyone also had this underlying feeling that when they went back, perhaps it would be difficult for all the leaders to meet up again once the war started again, not that they still weren't in a war.
On top of that, little bits still needed to be figured out by everyone before they moved out. After what they had learnt about Pure's coordinated attack, Earth wasn't a safe place for them any more, and they could practically trust no one. As if vampire agents working for the Dalki hadn't been enough, now they had to watch out for humans as well, all while fighting in a war.