Jeff Monken literally left Georgia Southern for Army, has experienced a bunch of success, and makes about 50% more per year than the guy Georgia Southern just fired, but they think he'd want to go back? Makes no sense unless he's just dead set on returning to GA.
There's nothing he could accomplish there that he can't at Army, and it would basically be a dead end if he's interested in a higher profile job. That's not even getting into how impatient GSU fans are. They're about to be on their 7th head coach since 2006, and pretty much consider you useless if you can't replicate Paul Johnson's results within your first year.
I do know that PJ keeps in contact with GSU's AD, and as recently as last year expressed interest in returning to coaching at some point. Not sure if he would take the job, but that should be the first person they reach out to. He might be the only guy the fan base wouldn't turn on after one bad loss.