Re: Why didn't the Federation salvage Empok Nor?
A better question is why didn't the Cardassians destroy Tarak Nor when they abandoned it.
They did leave booby traps behind, IIRC. Perhaps the thought of Starfleet and the Bajorans running all over the place trying to fix it up was funnier to the Cardassians than simply blowing it to smithereens...
In labor news: Longshoremen walked off the piers today. Rescue operations are continuing.