I think the lack of reaction is plausible: shock/surprise and a naturally-calm demeanor. There's no sense in shouting if there's no one to hear you. He only starts shouting when his son is visible.

(I have been calm in emergencies in the past, so I know I don't "freak out")

If it were me, I probably would have quietly said "fu.." under my breath while I just sat there either waiting for debris to pop up or try not to get eaten myself.