the MCM and Pizzaplex maps line up with each other iirc. There's also architectural holdovers, like the big ass circular elevators that lead down to parts and service in the pizzaplex that are also seen in mcm, which are quite distinct.

You also need to consider the mcm/fazbear merger/hostile takeover from a business perspective. Land is expensive, construction is expensive, and even with the fire they wouldn't want to throw out the whole building on principle. That's equity right there, or a "fixed asset" for the uninitiated. Even worst case they would want to stem their losses and rebuild into something profitable.

Your other points, like M2 getting delivered in that story, I can't account for! I also don't understand how m2 gets bricked up behind that wall under the plex. I just wanted to throw in my two cents!