The business of television disagrees with you heavily, as does logic and reasoning and every piece of rumor and info regarding the scenario that can be plucked from the interet
This show isn't an artistic statement that HBO is willing to take a loss on. It is a television show that needs to continue to press the story so they do not lose viewerss and subscribers, and they have no need to cater to upset book readers when they have a far more important crowd to cater to (their viewers).
This isn't even really an argument. GRRM is dropping the ball, it would be 100% his fault if the show finishes first. HBO will finish the series without him if he can't drop Dream of Spring by around 2017-2018. Period, end of discussion.