He had every right to pull his gun.
You can watch all 6 minutes if you like, but I’ll save you the trouble. Basically these bumpkins try being bad asses in their Toyota Pickup truck as the film themselves stalking and terrorizing this man and his wife in a BMW. Cut to time marker 4:21, that’s where it gets good.
The rednecks trap the man and his spouse in what looks like a no outlet, and the driver of the pickup pulls out a baseball bat and moves toward the BMW driver. Who then promptly pulls out his 357 magnum and turns the tables on the would be country bad boys. KARMA’s a B*TCH!