The failed drug test was early December when he wasn't in competition which is why is why he faced no sanctions from NSAC (cocaine is not deemed a performance enhancing drug). Had he been on it during the fight, his victory would have been overturned, he would have been fined, and he would have been suspended (because he would be a danger to himself and others, and the effects could have stunted his pain threshold - all of that wears off immediately and you get no long term benefit, hence not a performance enhancer).