You thought the sum of his 6-8 rep max for flat bench, row and incline bench would come out at around 600kg?
If we we're talking a bench, squat, dead total then I could see where you were coming from but right now I don't have a clue what you're on about.
What does HITT even mean? Did you mean HIT? or maybe HIIT although I don't know anyone who would quote weights lifted in a HIIT complex unless specifically talking about them.