This makes perfect sense in a couple of different ways.
During the behind-the-scenes making-of video of Metal Gear Rising: Revengeance (it debuted yesterday), people noticed the game was being controlled with an Xbox 360 controller. This gave way to speculation that new developer Platinum Games was using Microsoft's console as the lead platform.
But according to Andriasang citing Inaba's Twitter feed, the opposite is true: the PlayStation 3 is the lead platform for Rising . Here's a little studio history: with Bayonetta , the team dropped the ball because they only developed the 360 version; the PS3 version was handled externally. But they rectified the problem with Vanquish by making both versions. Furthermore: "Games are developed on an internal Platinum-developed engine, and PS3 is always the lead platform."
The reason you saw the 360 controller in the making-of documentary? That's just because it's used to control the game on PC for cross-platform development. Inaba concluded his Twitter monologue by saying-
"So, in closing, Metal Gear Rising's lead platform is also PlayStation 3."
Also, let's not forget that Kojima Productions very likely used the PS3 as the lead platform when creating those character designs, too. So it all just kinda fits together, right?
Related Game(s): Metal Gear Rising: Revengeance