Debate I had with a friend, bet the turn or not?

[phillydilly]

20+2 sit n go
level 1, 10/15 blinds
dealt AA in MP,
one limper, I raise to 50, two callers,
flop comes AQ8, two diamonds,
first guy bets 35 into a pot of 175, i raise to 100, not wanting to completely get rid of him, other guy folds,
turn is 8, giving me a boat, he checks and now i'm sure he's on a flush draw, so I check hoping he'll hit his draw,
river brings the third diamond and he goes all in, i call and knock him out

his arguement
checking the turn, there is no card that will let him beat me, and i can take his whole stack if a diamond hits, and the check may induce a bluff to take his stack again

my arguement
gotta bet the turn, if only 1/4 to 1/3 the pot, if he misses the flush draw, you might not get any more out of him, if he hits, you prolly will get his whole stack,


well? what do you guys think?