[quote=@TheUnknowable]
[@Burning Kitty]He's still fighting villains in this sector, he's just working with one to facilitate it.

Besides, Sinestro was still one when he conquered his home world, so it's possible.  Or I could have him go rogue and keep the ring if that doesn't make sense to anyone.
[/quote]

Sinestro was a genius who was able to hide it for years. Didn't help the Guardians ain't that bright and had blinders on when it came to their golden boy Sinestro.

John may be a great guy but he ain't as smart as Sinestro.

Villains fight each other all the time, doesn't make that action the action of a hero.