In a battle between rich athletes and even richer businessman the public relations war is already lost, but the owners apparently worried about the currently positive NFL lockout negotiations—which might, if they're settled in the next month, save the entirety of the NFL's season and preseason—are not doing themselves a big favor by leaking their uncertainty to the press. Some owners apparently believe the new deal insufficient, and negotiations are being held over to attempt to cure them of that delusion.
Neither side is especially sympathetic here, but the owners in the NFL have a far better deal than any other set of professional sports owners—no guaranteed contracts despite the brutality of the sport, massive profits, and a weak union hamstrung by the relative unpopularity of the individual star in the NFL compared to the laundry. That they aren't satisfied with the current CBA is already asinine; that they want more concessions still—well, they've earned the potential losses they'll incur if the season is delayed, which is admittedly cold comfort for NFL fans tired of the lockout.