I think a tight player as a rock will push on the flop when he flop the nutz because he doesnt want to see the flush draw hit. and in that case the guy played his hand wrong because every will call a 1/3 pot bet to hit a flush specially late in a tourney.

and by pushing with Kq on that flop lets you opponent know that you have it and you win most of the time. so by not pushing he is allowing a AQ of diamonds to stick around.

i like to push when i know i have the nuts on the flop specially late in a tourney.