Man, that's just a bizarre scheduling of things. My guess is that they originally planned the US concert during that time, but couldn't get the visas for it. Otherwise, it makes no sense to do the World Tour at that time period in the first place.
And it does make you wonder if the management knew they were going to have the shuffle when they planned the world tour. Based on how 12th gen didn't go to Houston, I don't think the new members will be going, either. Curses, I definitely would have thrown money at them to meet Yanamin in VIP.