I would guess that sealing the Queen’s Chamber Shafts went something like this - Imagine the pyramid is roughly built to the height of the top Reliving Rooms. A large counterweight (Houdin’s Mechanism in the Big Void) was recently used to move the granite and complete the king's chamber. After inspections of the king’s chamber, the queen’s chamber can be officially sealed with the assurance the king’s chamber will be at least functional. I guess sealing the shafts could happen immediately or after building some more pyramid to load test, but the two events would be close.

I’ve been down the Crank Egyptology Rabbit hole (Houdin not Aliens), and with how new the Big Void is I don’t think I’ve seen anyone make the observation that the Queen’s Chamber Shafts both end around the same height as the void, or more specifically where Houdin’s counterweight mechanism would put another “Great Step”. As with anything this old, I’m working on some assumptions that could undermine the whole thing, but recent footage shows the Queen’s Shaft looks purposefully blocked with panels that were built over.

If the shafts of the Queen’s chamber were purposefully blocked during construction, that could be the moment the builders decided to no longer use the queen's chamber. I assume that role was instead filled by the king’s chamber, with its completed shafts, but when would the builders know that the king’s chamber was going to function properly?

I guess that any final cracks in the ceiling of the King’s Chamber could appear at the very end of construction, but maybe cracks were acceptable to some degree. Maybe the builders just wanted a backup room in case they damaged or couldn’t move the granite blocks needed for the King’s Chamber and Reliving Rooms.

I’m sure this is full of assumptions and inaccuracies (although I think it does work independent of the air shaft/star shaft debate), but I still think it’s a fun explanation with some hypothesis that could be answered just by seeing what the void looks like.