I'm no tax expert by any means, but if those expenses otherwise qualify as "ordinary and necessary" business expenses under 26 U.S.C. sec. 162, I should think the answer would be yes.
There's nothing at all untoward, in principle, about an Olympic athlete's being taxed on prize monies or bonuses awarded for winning a medal. For Rubio to suggest otherwise is pandering on his part.
What if we can show you that other countries do NOT tax income earned outside of the boundaries of that country?
Mexico comes to mind, right away!
What if we can show you that other countries SPECIFICALLY exempt Olympic prizes from their tax rates?
What if America is made less competitive due to our tax policy?
And is this not a great way to illustrate that point?