Bit of context: This is a live tournament - regular locals play with a field size of around 125. Freezout structure with no-rebuys starting at 150 BBs. People usually play very tight except a few maniacs who try to capitalise on this. We were on level 4 or 5 where antes just kicked in. Everyone is very deep (70BBs +). 10 players in the table.

Hand: I was in LJ position with AQo. UTG+1 and UTG+3 player limped and I raised to 4 BBs. Got a call from Cut-off, Small Blind, Open limper and the limper behind.

Flop comes A,A,T (rainbow).
Everybody checks to me. I bet half pot. Cut-off folds, Small Blind folds. Open limper just calls and the limper behind folds. We go heads-up.

The turn comes 5d. The open limper just goes all-in quickly. Should I call or fold?

It didn't seem like the card mattered to the villain and felt like he decided it on the flop. I still have around 50BBs left in my stack. I didn't want to risk my entire stack. And usually people go for full value in these tournaments when they have it and don't bluff too much. So, i talked myself into folding showing the Ace(hoping he would show his hole cards). Unfortunately he mucked and took a large pot. I didn't have any read on this player as it was a new table that I moved onto. And for the next 30 hands, he played very tight. Nothing too loose.

My question is what hand ranges could he be donking for the entire stack? Why not let me bet the turn and then go all-in? And is this a tight fold? should i be calling in this spot?