Like the girl in the 2000 olympics stripped of her gold medal, for taking pseudoephedrine, even though she legitimately had the flu, he should be banned.
She took a banned substance, which helped her get over the flu. What about the other girls in the event who might have also had the flu, they competed sick because they knew the banned substance was banned, she had an unfair advantage.
Same with Crowley and the dons. You know it's banned (or you're too stupid to check) and someone else sits out the week, because they also carry a similar injury and DON'T take the painkiller, he gets an advantage. It's banned, don't take it.