They were given 18 months starting in 2006. They failed to comply. How does this make it a problem on the side of the FAA?
Granted, they were probably lax. The issue is still NOT an emergency situation requiring the grounding of AA's entire MD-80 fleet. Cabling problems rarely contribute to airplanes falling out of the sky.
Once the issue was discovered by/at AA, an agreement to work with the FAA to comply with the cabling tie requirement at the next maintenance cycle would have been acceptable under most circumstances. As ASOC noted, the FAA probably cozied up to SWA and let them circumvent too many inspections. In order to regain their credibility, they needed to come down hard on the next target - AA.
So, somebody had to take the blame for the complacency at the FAA. If the order was issued in 2006, as you noted, why is it AA's fault that it wasn't done before now? The ball is still in the FAA's court because they have the responsibility of spot checking to ensure that the inpections are being properly performed. Evidently, there are some FAA inspectors who were "pencil-whipping" the paperwork instead of doing what we pay them for.