If I discovered a dupe on test center- I'd have a huge moral dilemma on outing it or hoarding it. Once the patch goes live, then you could exploit it on your normal shard. However, the number of people on the normal shard would also be greater so it is possible the dupe was only discovered after the live publish by an honest individual, and maybe it was repentantly used on Atlantic prior to the hot fix, so that is the only shard that really had the issue.
However, that is a lot of speculation. The other one of a hardware issue is favored by Occam's razor. Could also be the case, and hence would explain why only atlantic is getting the revert.
Also, there was a problem with houses dropping items under the sign... this sounds like a the beginning of a dupe strategy. Who knows. I didn't see a new dupe bug submitted to ask chopper, but I also don't have a private section password. I did some googling for dupe bugs today, just of curiousity and there was an older one that worked (mechanics I can't find, but screen shots of 14 shrouds of death, vendors with identical items, etc..) but can't find anything current. So, I'd still favor bad hardware.. If that's the case, I can argue against total shard revert, but is it possible to revert a specific account back on another shard so if you lost everything by transferring to ATL, you can have your account reverted on all shards to claim your lost transfer. I mean, they should have some record other than the character itself for a character transfer.