Doyle Bruson on PSI interesting hand

[TStoneMBD]

I figure with the WPT posts on here and their acceptance I'd post an interesting hand I saw on PSI. The content of replies here is significantly better than any other relevant forums, which is why I posted it here, but let me know if this is not good. both players have around 130k

Brunson is Q9cc and limps for 2k.
Ivey completes in SB with 83o
Lederer checks BB with 63o

Flop: 76Jmonotoneclubs
3 checks

Turn: 2s
Lederer bets 3k
Doyle calls
Ivey folds

River: 8d
Lederer checks, Doyle bets 25k (2x pot)

can someone explain what doyle is thinking here betting 2x the pot on the river?