[Lmn55d]

I think the sum of:

1. weaker kings (lots of uknowns play K2 etc.) that won't value bet
2. flush draws that paired the 9 or T (Q9, J9 etc.) and will call
3. flopped gutshot (which all paired) or pair of 9s that will call.
4. and aces that will value bet if checked to

is greater than:

1. The amount of flush draws that will bluff but would not call a value bet
2. The amount of weak aces or otherwise better hands (KQ) that checks through.

Thus I'd bet. I don't play 20/40, but I know many unknowns in 10/20 play a wide range of weaker hands that are paired here and would pay off, despite the A and K on board.