IMO the rollback would be the better option, then leaving the coins in the hands of the thief.
Whats the problem with a rollback ? Basicly nobody looses anything , just the thief.
Are you okay with rolling back the blockchain every time someone gets their money stolen? How 'bout when someone makes a purchase and the seller never ships? Do they get a blockchain rollback? Lost your wallet.dat due to hard drive crash... Rollback?
How much credibility would OPAL have once you start down that path?