I don't hate A9 preflop from the SB, because you get in cheap. Especially at a loose table. You're looking for a flop you really like.

IMO, this is not a great flop for you. It's ok but not great. And I don't much like the flop bet. You're behind AT AJ AQ AK not to mention all of the two pair hands and sets and flushes. If someone behind you flat calls you have no clue if they have a made hand that currently beats you or just the flush draw to the nuts. If the fourth flush card comes, are you good or not? You're out of position with no way to find out.

And I really don't like the flop push. Especially if you're running bad. It's a very risky play and may well be -EV. He may have the FD but he could just as well have two pair. Everybody loves to get frisky with two pair. And he could be one of the less donkish players and be raising with the set or a baby flush. In any case you have zero fold equity and a mediocre hand.