Characterization. Ghostface is rarely depicted as speaking while physically on screen in order to aid in concealing the identity of the character behind the mask.

We don't get to see Ghost's face during the cutscene, but it looks like it was modelled after all. Considering Ghost's gruff voice and mysterious demeanour, it might be a bit of a surprise to see that he just looks like a normal bloke, one that spends a pretty decent amount of time on his hair.