All the folks who respond with, "Lebron dopes, too," are missing the main thrust of the argument. Unless whatever Lebron allegedly takes made him so much physically bigger than his competitors. I don't know enough about Babe Ruth to engage with that part of the argument. But the Lebron deal makes sense--he is an incredible ballplayer, but he would not have achieved the superstar status he has were he not so big. I have never seen such a combination of speed and grace in an athlete so big and strong--not even David Robinson. And Lebron is even heavier!
This in no way proves that Bolt is clean. But he is as visibly physically different from his main competitors as is Lebron. That's why the analogy works, regardless of whether he's clean or not.
As my handle indicates, I follow University of SC sports. Take as another example Jadaveon Clowney. There are plenty of seriously freakish athletes at the D1 and NFL levels. Indeed, the #1 recruit this past year was also a big, fast DE. But when the experts are asked, "so, is it reasonable to expect him to play like Clowney," they answer no. Clowney is a freak among freaks--allegedly ran 4.46 at 270 lbs this summer. It is at least theoretically possible that Bolt is a freak among freaks due to the obvious physical differences in a way that would be much harder to argue for a Gay, or Powell, or Carter who seem physically so similar.