That does not change the fact that steroids make it FAR more likely for muscle tears after years of steroid use. For all we know, it could have been purely bad luck, but the side-effects of steroids make injuries like this far more frequent.
You're better than this. I don't care if someone used steroids or not, if a player rolls on his knee the wrong way its going to tear. Steroids have as much to do with that injury as the color his underwear.
I am not debating the legality and cleanliness of the hit.
what you are doing is looking for an excuse to blame steroids or bash a guy who took them. He was hurt because he got hit from behind on the knee.