You started with 18BB, and if CO had you covered, I could get on board with a 3BB raise to play some postflop with a very loose player in position. Here however CO only started with 12BB, and that is just not deep enough to make postflop play a good option. So I would just jam over this limp, even though you are risking a bit more, than you ideally want to, against the players in the blinds. This however is not a big deal, because they are rarely going to give you action, and its not like, you can raise-fold AQ for 18BB anyway. So if someone in the blinds happen to wake up with AK or KK, you just accept your fate and play the next tournament. Or you suck out on them and dubble up.
I am ok checking back, because the SPR is only 1, so its very easy to get the chips in later. And its not a check-back, because I am scared to be behind. Its a check-back, because it allow him to potentially bluff
Snap call. First of all you are never folding AQ, when the SPR is only 1, not even if you missed the flop completely. In that situation you jam flop for max fold equity
. And this is why, your preflop sizing just dont make sense. In this situation he could of course have a better hand like a flush or straight. Thats possible. But he could also have a worse hand like a worse two pair or flatout nothing. And even when you are behind, you have 7-9 outs to the A high flush and 4 outs to a boat, so you are never drawing dead. Unless of course he has the straight flush, but we are not worried about one combo in poker.