Really? did you see what happened to derrick rose when he played garbage minutes with no purpose? Lebron shouldn't be playing when there is nothing to play for. It's too risky and really pointless from a business/basketball perspective.
It wasn't garbage minutes. The 3rd quarter began, the Heat were up by 20(not a blowout yet with that much time remaining), Lebron was in a groove and wanted to keep playing.
These men are pro athletes and Lebron has carte blanche to do what he wants as the best player in the NBA. There were plenty of games where Michael Jordan would keep playing with a big lead late in a game. Especially when he was motivated based on what an opponent said prior. It's called being a competitor with a will to dominate. I don't see what's so hard to understand about this.
Lebron is playing at the peak of his powers. Enjoy it while it lasts.