Good sportsmanship and great press.
That's gotta be worth money in advertising.
Yes, it is great press. Whether it will get him any money from advertising or not is hard to say. If you have any information on that, please provide links. But even if he does make money off of it, that will not prove whether or not he did it for money. Sometimes, doing the right thing for the right reason is rewarded, but that doesn't show that it was done for the extra reward. In point of fact, his doing this draws attention to the fact that there is more than one runner who ran faster than him that day, so it also is a kind of bad press for him as well. Otherwise, just knowing that he won the Silver Medal, one would naturally tend to assume that he was the second fastest that day. With this story, we see he wasn't even the second fastest.
Frankly, although I am frequently apt to think the worst of people (because they are often bad), in this case, I am willing to give him the benefit of the doubt and am ready to believe he did it for the reason he stated. If I won a medal and thought someone else was cheated out of it, I wouldn't feel right about it either, so his story is believable. When I win at something, I want it to be because I actually won, not because someone else got screwed. Of course, in this case, they were both losers, as Usain Bolt won the race. There is only one winner of any race, and the ancient Greeks understood that in the original Olympics. They didn't give you anything if you came in second. And the winner wouldn't get something permanent like gold, but would be given something like an olive wreath, to signify the transitory nature of victory. The winner at one Olympics was not the best forever, just the best at the moment. But I digress...