No one is saying, this T20 win as a revenge for the world cup's loss and if someone gave you that impression then you watched/heard from someone who is not in their right mind.
This isn't even the won of the series just win after the 3 days of the final and that's some relief that's it.
Anyway, I would say if India can whitewash Aussies in this series then defintely it is a statement from team India about the upcoming T20 WC.
World Cup Final was the only match they have to win. Now the people when say how they loss and when they loss? These all are just statements of the people and they have even different thinking.
Most probably the India team may be won the World Cup but the Australia were quite amazing on their Final at the stadium thus they provide some good cricket and they won the trophy.
Another chance of their t20 series so it is just the series and it can't affect the Australia Moral at all because there would be some win loss situation in it and that will not be that hard for the team India.