Complicated and risky plot (he teach well his future enemies). Sacking Dumbledore doesn’t seem worthy such big risk. Quirrell now has the possibility to teach future wizards what he thinks will serve him, is impossible to fire, has influence on Harry, and Dumbledore doesn’t seem to get much value out of being head of the Hogward.
I think Quirrell wants to unite wizards using some external enemy, and conquer the world/stop muggles from nuking themselves. Harry has great PR, so he’ll be the fuhrer of united magical Brittain, and Quirrell will provide common enemy somehow to make it easier for Harry to rule.
Jumping in time just 6 hours back indicates to me that in the computer that is simulating MoR universe data is kept with 6-hours long cache.
As to Atlantis—they found a way to get out of the box—one level up, and they’ve left some cheat-codes for people that are still in this simulation. That also explains why some very important figures (like Dumbledore) think MoR runs on stories—somebody outside of simulation changes the simulation accordingnly. Maybe this simulation purpose is to make the best stories?
Also explains why prophecy works for more than 6 hours into the future—because simulation has some invariants, that make for best stories, and seers can well, “see” them, but only for very important events, and only guess ral meaning of these predictions. Hence mysterious prophecies.
What it doesn’t explain—why cheat codes are in latinised English.