I read over a few of the posts & wanted to share my input(4 years active duty; US military, 20+ years in armed/protective services-security);
Mindset & training are important but what a few forum members may not be aware of is that armed attacks/robbery were common in central Florida. The G(Florida armed/licensed security) officer used good tactics & judgement but probably keyed into possible threats and the proper counter-measures BEFORE this lethal force event took place.
These new casino locations & gaming sites draw in thugs looking for a quick score. I'd opt for a tactical/LE type 12ga shotgun knowing multiple subjects may attempt a "take-down" robbery.
I also avoid the "what-if" game. You can second guess & talk yourself in circles doing protection/security work. The main point in armed security is to maintain a "hard target" and to find/remove any weak areas or problems in a security system. Thugs & gang members do not want to work hard or deal with well armed, well trained foes.
As combat veteran & top instructor; Clint Smith says; "if you look like food, you will be eaten."