I don't know enough about competitive running/sprinting to comment too much, but I do think there's still a large gap between that particular runner not trying their absolute best as it's not a final, and the charade of jogging just ahead of the person in second for two thirds of the race to ensure they don't win by too much.
The fact is that everyone else in that race was probably trying their absolute best, and it wouldn't have been good enough even with the winner deliberately slowing down to keep the gap smaller.
As SilentWitness has pointed out, we want these athletes doing their best anyway so we can actually base decisions on data rather than feelings.