It wasn't Sony that stated it. If it were Sony, then I would be dubious, but it was the developers.
Here is the quote:
Guerrilla's Managing Director Herman Hulst stated of being able to develop exclusively for the PlayStation 3: "It's a huge benefit. If you're developing a game on multiple platforms there are restrictions you always have to take into consideration.
"We are taking huge advantage of the architecture of PS3. I firmly believe that what we've shown we can get out of that machine would be difficult, if not impossible, to deliver on a competing machine."
Ter Heide went on to point out the advantages of Blu-ray on the PS3: "To make it simple, the Xbox 360 doesn't have SixAxis or Blu-ray. PlayStation 3 does. And for us that's a really big thing. The level you've just seen is 2GB. We really need Blu-ray to make the game. I don't know how you could fit it on Xbox 360 without taking some shortcuts."
