They aren't the same meaning though.

The writer's analogy is much more accurate. MJ is widely considered the greatest basketball player of all time. To say someone is the MJ in a sport is saying that someone is the best in history for that particular sport. This kid doesn't even have a single gold medal.

Lebron James, on the other hand, was extremely hyped up as a high schooler. Everyone pretty much said he was going to be the next MJ. The potential for LBJ was limitless; same goes for the weightlifter.