Not sure why some people are baffled by the decision to focus on the larger installed bases(PS360) last, it makes sense in a unique case like this.
6 simultaneous versions of a game, is a bit much, even for Ubisoft. Not impossible, but definitely ties up a lot of man power/studios. So let's assume for the moment that this the reason for doing some versions later. With that said, given the decision on which versions to focus on first, and WHY, it could easily have played out like this:
"We can't afford to have development of this game lag behind on next-gen - where our game is also best represented - and possibly arrive late. This is where our future will be, so we need to make all the right moves here. This game could be a system seller, especially if next-gen consoles are the only consoles with the game initially. We could focus on current gen consoles later, because a combined base of 100+ million current-gen-only gamers guarantees good sales, regardless of when the game arrives. This would also allow us more time to fine tune the game as best as possible for current consoles."
Not saying that's how I believed it actually played out, just saying that it's very easy to justify and understand why PS360 version are the last focus.
(The same thought process should be applied to Wii U, especially if sales are to pick up. Arriving late there should be avoided at all costs. It seems they are up to the task, having another studio work on that version as we speak. Hopefully they do a good job).