Riding in the back is how he won. It doesn't show he doesn't care about winning, just he opposite. It shows he thinks there are going to be plenty of accidents and that riding in back until the last possible moment is the best way to be avoid those wrecks and be around at the end. Harvick did it most of the day too, but decided to stay up front one restart too soon.
Hamlin isn't the first one to successfully follow this strategy, and it isn't the first time the team has used it to get a plate win. Like you, I dislike it when a car that's been in the mid-30s most of the day is able to win a race. But that's pack racing. I dislike the strategy but I can't fault the #11 team for repeating what they've done in the past; not when doing it often gets them a win.