The FA in question was PHL-based and going to work. She also apparently had a legal PA concealed carry permit. Having the weapon in her work luggage was stupid, no doubt, and she deserves whatever consequences under the law or her employment might be forthcoming.
The article I read said she was going PHL-DEN, not DFW. Regardless, both of those markets are US-mainline only (I think Republic does DFW on weekends occasionally), which makes me think she was probably deadheading. (Or the media got it wrong, which would hardly be a surprise.)
My highest disdain in this case is for the CITY OF PHILADELPHIA POLICE OFFICER who was apparently attempting to unload the weapon and render it safe when she accidentally discharged it. (The story I read identifies the "discharger" as a female PPD officer on airport duty.) That a law enforcement officer was so careless in handling a firearm really galls me ...