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?
Rolling Back due to one theft from one place is one thing, rolling back due to a bunch of n00bs, downloading anything willy nillie is another. Fact is this, in this instance, a roll back would be poor... another fact.. its not going to do anything impressive till those coins are sold.
Edit(added): You can thank the dumbasses that dont verify anything, click random links & dl/install anything , for OPAL going from a nice volatile mkt, to a MAJOR long play @ best.
Edit Prt 2: (Added) More than likely the same types that go to phishy 'news' sites, add every one on social media avenues, and buy IPO's.