I actually agree with their decision, they just wanted to respect the continuity. It would have been odd if suddenly the ghost had a different voice with no explanation. And let's face it, there wasn't much of a chance of Dinklage coming back anyways. Not sure why they went with him in the first place because of that.

Probably Activision flexing their wallet, look who we have doing a voice, that guy that's really popular at the moment. Nothing against Dinklage, I'm just surprised he took the part to begin with.