How do we know he wasn't on something even during the ultimate fighter? Back then I wouldn't even be surprised if they weren't tested at all.
Reminds me of baseball where your have to deal with deciding if the cheating was bad enough to ignore what they did for the sport. Don't let Bonnar in the hall of fame, don't let him be an analyst, when he comes up say nothing but good things. People will forget....most people who pay attention to the UFC probably aren't even aware he tested positive at any point.