Whats as impressive as the weight is the raw strength required to even get into the hip thrust position LOL ... with that said in my experience hip thrusters work well with a lighter weight and controlled slow form ... to me a hip thruster is one of those exercises where you get a good benefit from slow strict form not muscling it up.
I'm not saying he does or doesn't (he's a genetic freak of course) because I have no idea, but these guys have to love it if they get tested mid season when they are most likely going to be off. It allows them to take advantage of the opportunity to show everyone "hey look I tested negative!"
Yup, Lance Armstrong didn't use anything either, that's what he said anyways. Wait a minute, turns out he was using a cocktail of PEDs. And now we are supposed to take James Harrison's word for it? Not sure if that's the most reliable source. But regardless if he uses or not, playing at the level he does at 39 years old is amazing.