They could be attempting to retool it. Or, from a marketing perspective, there is no reason to send it out there to get beaten up on. If Tanabe is confident it is actually a good game and does not show well, maybe the best course of action would be to release it and see.
It has a hard release date. It's being sent to die. Thought it'd be big, but it was another case of misreading and not understanding the Metroid fanbase.