It's rare, extremely rare, but possible. Not sure of his weight room numbers, but Bo Jackson could probably bench a small car (hyperbole alert), and most people have zero suspicion that he 'roided up.
Bo was an absolute freak of nature, and there aren't many like him, but TR is a freak in his own right. It wouldn't surprise me if TR did juice, but I believe it is possible he could have put up those numbers clean.
Hm. I'm young, only 19.. so I didn't "know Bo", and really have only heard stories about him. That being said, I watch that killer ESPN flick on him and was very impressed.
However, (and don't get me wrong, ever since I did some research, that guy is one of my favorites now) it's not that unlikely for him to have taken steroids.
I mainly say that because the main reason people don't think he did them is because steroids weren't common back then.. I disagree. Clearly they were extremely common in the body building world (you can notice a huge size gain from the guys in the 60s to early 70s and the guys from late 70s on forward).
I don't see how he couldn't have gotten his hands on steroids. He very well could have..
Now, that being said, geared up or not, that guy was an athletic anomaly. Just because your roided up doesn't mean you'll instantly be some sort of monster in all kinds of sports. It would definitely help you tremendously in the strength and endurance, but you couldn't all the sudden become a champ without some sort of athleticism (and in Bo's case, a whole bunch).
Just my two cents. Probably gonna get flamed. But that's just my opinion. No one could be 100% certain he wasn't using.
EDIT: And another thing, I bet it would be a lot harder for them to test for steroids back then and probably wouldn't be very accurate. Don't know much about how steroid testing works, but I'm sure that like all technology, it was worse back then then it is now and athletes cheat the system all the time.