I think he said that becaise he has a big ego. No one other than Mob is self aware in this world.
The fudanshi manga guy and mind reader are kind of aware lol
Even if he DOES know, MC can't say anything because that could also be a flag event lol. Being aware of how the world works doesn't always stop you from being part of the machine, so to say.
YEAH that dude was in mobs head in the show lol
WAIT HE KNOWS??? I mean either that or he has a big ego and calls people mobs but other than that WOW