After seeing all the backlash, I can only assume that Frictional chose PewDiePie to promote the game to preempt the rage and fears that the sequel would not be exactly like the original game.
It didn't exactly work the way it was intended, internet denizens being the fickle little swine that they are, but Frictional's decision suddenly makes a disturbing amount of sense. They wanted to reassure the 'masses' that the game would still be full of moments that would make you jump and provide plenty of Youtube videos where people over-react to a computer game.