Although the question is worded poorly, there is a reason for the question.
Can we be honest here?
If he was a slow runner, most experienced runners would point at his arm action and say that it needs a some work.
Why give him a "pass" because he is fast?
Can we ask ourselves:
Do you think he could be even faster with better arm action?
If you had a promising young runner with that arm action would you ignore it or would you work on it?
The best quarterbacks work on their throwing action. The best basketball players work on their jump shooting. Just because someone is good, or even the best at something doesn't mean they can't improve by working on their form.