WTF was he thinking with that kid at the begining?

Denzel went from badass to dumbass pretty quickly during the opening sequence. As a veteran, highly skilled & experienced spec ops agent, he takes out an entire gang of dangerous gangsters & when he comes across a suspicious kid who's clearly connected to the gangsters he just killed, he casually turns his back on him, even after assessing him as a potential threat? Umm.. what? As just a random guy watching a movie, in real time I was dumbfounded by what he was doing before the kid of course shoots him in the back.

I understand it not being in his character to kill the kid just to be on the safe side but it would have been common sense to at least make the kid get out of the car to verify that he wasn't armed & then watch him leave the area, in an opposing direction. But nope, rather he leaves the kid sitting suspiciously behind a car door with his hands completely hidden & turns his back and does the slowest beeline walk of all time away from the kid, leaving himself completely exposed to a rear attack & gets shot like an idiot. Honestly this was so dumb that it almost took me out of the movie. If they needed him to get shot to set up his whole bonding with the local townsfolk plot, they easily could have come up with something that didn't make him look like a total fool. It would have been one thing if it was used as a plot point as a sign that he's getting old & losing his edge but nope. We don't even get that. Just a random, inexplicable brain fart that never gets brought up again. Very strange