I think seeing that pile of bodies (or maybe that demon) triggered some serious fucking trauma in him. Given how relatively calm he's been up to this point, that must have been some deep-seated horror in his past.
I think given this previous life experiences, I think MC didnt even learn how to control his panic and think well of the situation.
As far i can tell, he only base his decision on what he knows about the past, and if comes to shove, he relies on this cheat power to break through the scenario which is comparable to what happen to his previous life...