[quote=@KoL]I think there's no reason for her not to go (she would be simply ignoring the possibility that some one might die), but it's your choice nonetheless.
[/quote]

My thinking was simply that if Miyako felt the Primordial vanish then she wouldn't bother showing up, since trying to be a MG and have a normal life would necessitate not spending extra time with the former. And if there's no reason to fight or show up, she wouldn't waste her time. 

Obviously if there's a stage 2 then that will be different.