In the "EPCOT film" (October 1966) the Magic Kingdom is depicted as a duplicate of Disneyland.
That construction was the creation of the canals and drainage system. Jeff Kurtti (Since the World Began p.35) and Charles Ridgeway (Spinning Disney's World p.82) both back up the Bob Thomas account I quoted that construction on the Magic Kingdom began in 1969. So Walt did not die while Cinderella Castle was being constructed. Kurtti says, "Years of research went into the planning and design of this distinctive signature building." That though does not tell us when Ryman began his work on Cinderella Castle or why he continued to include an apartment for Walt Disney, even though he had already passed away.
I think you are trying to read way to much into things and looking for conspiracy where there is none. Even in todays modern building age where nearly every structure is drawn on CAD and can be modified far easier than old hand drawn plans it is not uncommon for plans to be drawn and finalized years before the first shovel of dirt has been turned. Once plans reach that stage they are typically not changed without very good reason. Usually that reason is "this does not work" or something equally as dire. Now lets turn the clock back 50 +/- years to an age where plans are hand drawn and most engineers are still using slide rules. If the original design completed before Walt's death called for an apartment the only way it would have been completely eliminated would be if they had no other choice due to a structural, mechanical, etc issue. "We don't need that room now" would not be a valid reason for redesigning the castle that late in the game. The room being left unfinished and then re-purposed is exactly what you would expect to happen to it given the circumstances.
But in order for that to be the case, the Magic Kingdom would have to have been significantly far along in its design process when Walt Disney died. I am also having trouble finding a date for when Vista United-Telecommunications moved into this space. The suggestions seems to be that they left some time in the early 80s (makes sense that the phone system would be upgraded in conjunction with the EPCOT Center expansion), but when did they get there? IF they were there on Opening Day, as some tellings suggest, then why? Or did they move in after Roy passed away and how long after?
What actually happened is what actually happened nothing more nothing less. The castle was designed with an apartment in it for Walt. Walt died before it was built so the apartment was left unfinished. When it was eventually re-purposed for VUT is irrelevant. That is what happened.
Then why has nobody ever discussed designing the Magic Kingdom while Walt was still alive? There is a whole story there that has never been told if Cinderella Castle was designed while Walt Disney was still alive. This would be significant because it would be a very different view of Walt Disney's last year.
The video to which you are referencing is the "EPCOT film" and was made in October 1966, two months before Walt's death. The only image shown of the "theme park" is a roof plan of Disneyland. The image is not even altered a little, it is the roof plan of Disneyland as it would exist in 1967 (New Orleans Square was nearing completion and the New Tomorrowland was under construction).
Pretty sure it's way too late to remove any room from the Contemporary. Steel has a bad habit of rusting.
The History Chanel is wrong. While the rooms were built offsite and slid into place, they were never designed to be removed.
Besides, can you imagine the lawsuits that would happen when someone didn't notice that a block of rooms had been removed.
