There is no friggin' way Flex ever had the capacity to squat 600, for a single or reps. Ronnie, yes, totally, and Shawn was a much better squatter than Flex, and he was maybe good for, oh, I don't know, six-ish for maybe two or, at most, three.
Wheeler just cannot stop lying. Or he actually belives his own bullshit. And as far as him being "natural" for that one show, he sure as shit had stuff in his veins during the contest prep. His system was definitely not cleaned out.