In this spot I would ask myself the question “If I jam over his lead out will he fold any pair”? It can be tough to answer and in a lot of lower stakes games who knows but most of the time on flop like that if he has any pair or flush draw he's probably going to call. It's hard to believe lead bets and because the board is so bad it's a great time to lead out with a 99 type of hand he might of flatted with if you wouldn't believe him because you will insta shove and if he had a hand like AK he might even call suspecting you show up with worse aces that haven't paired.  You have 6 outs so your not dead but I'd feel better about it if I thought the player was capable of folding at least some pairs here which I'm not sure about. 

If you ever seen this guy check something decent come over the top of a bet or seen this guy lead out and then fold to a bet that should be going through your mind as well but without that completely unsure I don't think their is a harm in folding since you are so deep which you can find better spots against what is a soft field imo.

I liked the way you played it preflop. After he leads 1200 on the flop, I would just fold.