It's simple. Agreeing to a joint-venture in a potentially multi-billionaire dollar piece of property isn't like buying a 7-Eleven franchise. I work in the movie business and mulit-year delays are the norm. Again, this is a venture potentially worth billions... That kind of deal unfolds at its own pace.
I don't have a problem with them kicking the tires. They paid for the privilege and we will be further along when the results come back. If they want another extension they should expect it will get progressively more expensive to do so.