Yeah, it is because of the Bobby's, its so they can focus on the game for trouble, and they are not overstretched, like they would be on a saturday, if United and/or City were at home.
Especially the more 'equipped' males.
Anyway- I'm really looking forward to this new kit coming out, it looks quality.
I'll be getting it the day it comes out. Whatever the date might be who knows...