Speaking as someone who has trained along side Lomu in his prime (not with him just in the same gym) what utter bollocks. Possible that he was doing partial and heavily assisted reps with that weight but if anyone was to say, even a full unassisted single with that weight, I'm afraid it is a lie.
I've trained with and alongside some very strong bodybuilders/strongmen and for reps on squats the best I have ever personally seen was the following:
amateur bodybuilder weighing in around 320 pounds squatting 575 for 12 fullish reps.
A strongman competitor, who must have weighed around 350-360 pounds at the time and taller than me by at least a few inches, I'm guessing 6' 8 ish squatting butt to the floor over 600 pounds for 12. Also watched this guy do reverse grip bench press with 300 pounds for 40 reps like it was nothing. Not saying these guys are exceptional but having personally witnessed it was pretty impressive.
Also, a former world powerlifting champion who became a bodybuilder (who competed at I believe around 230 pounds or just less than that) I watched do 400 pound bench with basically perfect form for 10 reps at around his competition bb weight. Thing that sticks in my mind about that is he basically failed on reps 11 and 12, paused on both reps with the bar on his chest and then just exploded it up, couple of inches at a time and only just managed to rack it on the 12th. That was pretty impressive.