The problem is Johns and generally anything he says is law around DC, even more than Morrison or whatever.
I mean, look at the recent round of Blackest Night action figures announced in Monday's solicits, which feature a Wonder Woman apparently somehow affected by the events of Blackest Night in a manner which will likely be complete bullshit but has to be done because Johns likes to think he understands the character.
It's the exact same thing here. Johns is touting his little Legion and because editorial are seemingly scared to say no to him given he's their biggest moneymaker, right now, he gets his wish. I don't know why Shooter couldn't have been allowed to carry on with the threeboot book.