http://www.guns.com/indiana-man-filing-lawsuit-fired-ar-15-11051.html If I were CEO, I would say that I didn't want an employee who was a liability regarding the negligent discharge.
It appears that the AD occurred at an apartment complex that is serviced by the company.... so it may not be an open and shut case.... Still he not the sharpest crayon in the box for not clearing his weapon...
The article states that the AD happened while he was off duty, and that the reason given for his termination was that he violated the company policy, however company policy is in violation of state law. Had they fired him with no reason given they would have been fine.