MLB knew all this shit before the agreement to purchase. Sounds more like them saying to him: We let you in if you agree to move.
I don't know what the legal implications are of Crane just saying the deal is off. I suppose he is liable for something in that case. More likely, he can continue to wait them out, leaving the decision in their court: take me and the Astros as they presently are (in other words, I will not agree to move) or reject me.
I also wonder if an MLB statement of "If you won't move, we won't approve" would open them up to a lawsuit from Drayton.