Well my original comment still stands. If he was using hacks (i.e. Cheats) then he does not deserve to play.
If he meant tweaks that he'd used before on a tweak enabled server and they no longer work, then that's just tough, you mess around with the game who knows what problems might show up.
And I wasn't implying he made the hacks, as you say the vast majority would not have a clue how to, but it's very easy to download cheats that someone else has made.