Decathalon 1500, why did they just let that guy in third place win?

I keep hearing about a "world record," but he was in third.

The guy who had the lead for the majority of the race was obviously holding back, watching them catch up to him. The guy in second was actually pushing but the guy in third was faster.

The guy in first just moved to the outside and started to slow down, and even waved him past. What the hell, how is that sportsmanship? He was actually going to win the race (and the possible "much talked about" world record) at that pace, why on earth did he let him win?!