Were you watching? Truex spun Johnson AFTER the race to display his displeasure for Johnson's reckless driving that knocked them both out of winning contention.
Johnson was eliminated because he, unlike Truex, was 13th in the standings, he would have finished higher if he had driven careful enough to not wreck in sight of the finish flag.
Truex wasn't eliminated because he, unlike Johnson, had enough season points to remain in contention, he won 4 races and had 17 top 5 finishes, Johnson had zero wins and 2 top 5's. Notice Truex was even ahead of Johnson in this race until Johnson short cutted the corner while sliding backwards into the race leader.
Jimmy was an excellent racer in his day, can't argue with 7 Cups, but his career is sunsetting. Truex is still on the rise.
I'm a fan of Fan of Fords and anybody who wrecks the 18.