So what? It's sports. Entertainment. For fun.
If there were scores of athletes showing up with amputated limbs, winning everything and distroting the rankings, then this discussion might be worth having. But these are the statistics so far:
Long jump competitions won by peoploe without prosthetic limbs: A shitload
Long jump competitions won by peoploe with prosthetic limbs: One
You might argue that he is getting an unfairly large share of the prize money, thus hurting the other athletes, but it is probably the other way around. He's drawing more attention to the sport, hence bringing in more sponsor money, to the benefit of all.