This is your shot:
Capture.JPG click the pic to enlarge
Using Google, I put "feet on the ground" at the site... in the view here you are across the parking lot at about the same distance you would be if you were the BBQ owner... the front of the IHOP is in front of you... the entrance to the IHOP is to the right of the white and black vehicles parked in the front row, under the gable (I think).
How is that shot looking to you, now?
In order to get close enough to be effective, there's a lot of parking lot to cover... we don't know how busy it was on that day... there could have been more vehicle cover... or not.
Gabe, you (or your instructors) might be able to make the shot, would that be a one shot kill? Sure, a non-moving paper target at 100 yards is "doable;" braced, on a range. Head shot? Disabling shot? Red dot?
No, for me the shot is not doable.
Could I get close enough, in time? Could any ordinary Joe? Is this what is EXPECTED of those who carry for SD? I don't think so. Would LE make this shot with a pistol, or call for backup SWAT sniper, or run in gun a-blazing?
To train for this is the "Sheepdog" mentality that it is incumbent on CCW permit holders to be all the things we are not supposed to be... Super hero warriors, LE, and trained killers all in one...
In a scenario I recently posted I asked "If you saw a KNOWN badguy shooter 10 feet away, drawing a weapon on a teller to repeat what he had already done once before (get the money and shoot the teller anyway), Would you shoot?" I say yes to that, it is a shot I can make.
This shot, presented here, not so much. Would I try something? maybe. that's the best I can offer. MAYBE>