That's a laugh! It reminds me of when Casey Anthony was released from the Orange County Jail(
www.BestJail.com ) , the embedded Orlando Sentinel reporter stated the corrections officer escort had a "AK-45".
The county jail officers used Glock 21 .45acp sidearms & HK UMP .45acp sub-machine guns.
Im curious to know too if the security guard had just a AR-15 5.56mm or did he have a sidearm too?
Armed guards at fast food places or casual dining restaurants are not uncommon. There have been "take down" armed robberies of places like Denny's & Perkins in my metro area.
While I was in Panama(Panama City) in the 1990s, I saw several restaurants & stores with guards armed with 12ga shotguns & rifles.
Clyde