interesting WPT tournament hand

[SossMan]

major TV tournament.

Hero is UTG w/ 7k.
Blinds 150-300 a25. Hour levels.
Hero tosses out a 1k chip intending to raise, but he is an internet donkey playing in his first live tournament and doesn't know the one chip rule. everyone at the table knew his intent.

He has AKo and a very tight (prob weak tight) image.

He gets 5 callers. 6 to the flop w/ ~2k in the pot.

Flop is KQx rainbow

He bets out 1200. Young aggressive name pro next to act flat calls. Everyone else folds.

Pot is 4400 and hero has 5500 left.

Turn is a small card putting two spades on board (no spades for hero).

Hero checks.

Young aggressive pro immediately slides out four 1k chips (4000).

Hero?