Why do we let Batman just walk around free?
He helped to nearly destroy the universe with his Brother Eye project during the infinite crisis.
He nearly, singlehandedly, destroyed the multiverse because he couldn’t keep himself from investigating nth metal during the rebirth crisis.
Cause he’s BATMAN!
Perpetua scoffs at this “Batman” you speak of.
I’d wager Manhattan is more of a major threat to life as we know it than Batman. [drums nails on desk & waits for replies]…
I think you misspelled “Adrian Veidt”
Could make for a fun storyline though
The anti-monitor literally destroyed the multiverse.
Barry Allen did destroy (and then recreated the universe) in Flashpoint.
Those who actually have destroyed a universe or more are far more dangerous.
All the heroes… Including BATMAN, have certainly had there moments of great error, and great mistakes that risked lives and even risked the universe (as They know it, and as we know it). But what makes them great, is that even though mistakes are made… They never give up. They never back down.
As far as great DANGERS to the universe… any change in Superman’s character, or loss of his temper (example, when Lois Lane, son, or Parents are in great Danger) could be the end of us all! 
“Let” him go free? Try to stop him.