It has very very little to do with furlough. There is nothing contractual that would prevent them from doing it now, even with TSA flying AMR owned airplanes. The arbitrator ruled there was no violation by them simply operating the airplanes.
It has much more to do with the previous 2002 grievance. In the body of the arbitrators ruling he stated what would be a violation. When they transfered the MIA route recently to TSA it completed the exact scenario the previous arbitration had defined....
Based on that ruling, and the fact that there is precedent for suing for damages (AMR sued one of it's pilot's unions a few years ago) and being awarded damages plus penalties.... AMR decided it was best to pay Eagle pilots to fly the AMR airplanes, rather than pay TSA to fly them, AND then later be forced through court to have to pay Eagle pilots for it too.
If they had not transfered the route, this wouldn't be an issue.... but they did... and they got called on it. When their lawyers saw the MIA grienvance and reviewed the prior decisions, they realized they screwed the pooch... and would end up paying twice for the same work.
They really had NO choice but to recall the planes, because as soon as TSA started doing Eagle routes it completed the last element required for a violation under a previously argued issue.... Judges don't like it too much when there is a runling on something, and then a few years later you do exactly what they told you, you couldn't do without creating a violation.... that tyically results in large awards, with hefty penalties and punative damages.

As others have said, the attrition rate is still fairly constant, and people are still taking the LTLOA's... there will be no need to furlough. Eagle is already attending new job fairs in anticipation of resumed hiring.