Given that he's only 21, and the Olympics this year were a year late, it would seem like a no-brainer to try for another cycle. He'd only be 24 at the end of it not like 32 or anything.
WWE isn't like a sport like the NFL, in that charisma is what sells. If he's charismatic, the lucrative contract will be there in 3 years all the same, except he might have become one of only what, 3 Americans to win multiple Olympic gold medals?
I personally feel like this is a short-sighted mistake given his age, the shorter cycle, and the fact that losing a step athletically really has no bearing on WWE success like it would in a traditional sport. He'd have likely made enough money over the next 3 years anyway.