Sounds like that may have triggered the attack.
Your post seems to back up this theory.
Police may have picked up the shooter’s trail because he threatened someone with a gun nearby. Reports were that a man with a gun confronted a building manager in the Arkansas Baptist State Convention office building a few blocks east of Democratic headquarters and said he’d lost his job. He pointed the gun, but didn’t shoot. He fled in a vehicle whose description was reported to police.
Gwatney was an executive in a car dealership group, a business in which employment changes are not uncommon. Rumors immediately arose that the shooter might have been a disgruntled former employee of the Gwatney Chevrolet dealership in Jacksonville.