This seems to be an MTT hand. You might want to post in the MTT forum.

Since the stacks are fairly deep, this plays like a cash game spot.

In general, I like to play a 3-bet or fold strategy from the SB. A hand like AJo doesn't flop super great and there is some value in knocking the big blind out of the pot. However, if the BB is passive, then flatting is often ok.

The problem with flatting AJo is that it is very dominated by MP+1's range. MTT ranges are a little wider than cash game ranges (due to antes). So, you're left with the situation here, where you're often guessing about your opponent's range. Your own range is weak and narrow because you didn't 3-bet.

Without reads, I would probably call turn and probably call most rivers; because you don't block any flush draws. There is also a chance that he's value-betting AT or some low suited Ace, or that he has AJ himself.

Moved to MTT.