By that logic if a mcdonalds employee hits me with his car on his way to work in uniform i can sue mcdonalds ?
The only reason they can sue HPD is because the only reason he had a gun with him is because he is a HPD officer and no private citizen is allowed to carry one. If CCW laws for the state were different and other people could carry firearms, HPD could argue that he was carrying a civilian just like any one else can and as such his actions are not a representation of HPD.
If the McDonald's employee is on the clock, maybe going to do a bank drop or pick up something from another store, then yes. He was not on his own time, so the store, franchise, whatever is appropriate can be sued.
If the guy was just leaving work and clocked out, then McDonald's is technically okay. However, the general legal tactic is to name McD's, the property owner if in a shopping center, and the company that striped the lines in the parking lot in the lawsuit! The objective is to get those deep pocket companies to settle. If each decides $10K-$20K is cheaper than defending against a $100K claim, they have justification to just pay and make it go away.
$20K x 3 "pigeons" = a good pay day!
I've read where someone who slipped and fell in a mall food court due to a small spot of liquid another customer had just spilled sued the mall, the security company, the janitorial service, and every single company operating in the food court! It's a racket!