I actually liked that, if I remember right there were entries written by him in the game where it more or less seemed he was barely holding it together. Him being silent might have been a coping mechanism basically saying "If I do what's required and don't interact, I might be able to get out of here alive and just forget this nightmare ever happened "

Him talking later in Dead Space 2 makes sense from that perspective as it's now "the nightmare never left me, it stalks me awake and in my sleep, what the fuck do you want!"