Zyg, what experts said this? In 1999, I trained for a powerlifting meet for twelve weeks and I put up those numbers at my first meet, when I was 19. I find those figures to be very low relative to many people's potential.
The thing I think is weird about them, is that MOST of the PLers I see have comparable squats and deads, and then a different bench number. Like 500/300/500 ...the squat and dead are always closer.
Natural or not, most people will never deadlift 500 let alone 700, so if he is or isn't doesn't matter. If drugs made the deadlifter I would know alot of 700+ deadlifters.