Even though it's obviously not him…

Ubisoft's first official response was that it would take too much time and effort, anything said after that I am unaware of.

Source

Had female characters been included, Ubisoft would have had to "redo a lot of animation, a lot of costumes." In effect, "It would have doubled the work on those things. And I mean it's something the team really wanted, but we had to make a decision… It's unfortunate, but it's a reality of game development.

For as big as Ubisoft is, that just seems like a BS excuse.