Jason was right to be confused about the stunt happening. Effies exact quote during their one-on-one meeting was:
Quote:
I see a path, a very tenuous path, to do the stunt the way that you want
In the exchange it's true that Effie never directly said that they can do the "flip", but had I been him, I would have certainly understood that to mean the stunt was on the table.
It seems from the way the show was edited, Jason's lack of appreciation for Effie's efforts finally bit him in the ass. It looks like she held it against him and so when the meeting with HBO happens later in the episode, she plays some serious semantics about the stunt never going down the way he ever wanted.
She comes across as the villain, but ultimately someone has to pay for all this. His air of entitlement and lack of compromise is not noble. It's ultimately self defeating if you can't rally the truly important people to your side. Read: those with the $$