SDSU got a lot of flack for how they handled this, but I think both sides of the MW issue have handled it about as well as they could have.
SDSU thinks that they are leaving and wants to avoid paying 17 million extra, so they sent a somewhat ambiguous notice that they plan to withdraw in the future. I can see them hoping that either (1) they will be able to argue later that this letter was their notice of withdrawal and thus they should only have to pay the 17 million or (2) this will make it clear that the Pac 12 is at fault and maybe the Pac 12 will be more likely to help them out with the extra money (e.g., loaning them the money and taking it out of their payments over the next several years).
The Mountain West did the right thing in treating it as a current withdrawal, thus forcing SDSU to clarify whether it is a withdrawal. This clarification makes it much harder for SDSU to claim it was the necessary withdrawal before July 1 required by the bylaws.
Finally, SDSU had to clarify that it was not a withdrawal because they do not yet have the Pac 12 invite and cannot risk being left without a conference.
Both sides are dealing with a shitty situation that is outside of their control.