Actually, what makes this slip-up even weirder, is that just before they (Otho and Charles) lift the table, as they're walking into the attic, you CAN see one or two guys in jumpsuits just at the left of the screen. Mind you, it still doesn't explain why they're there, and they're never mentioned at all. Weird.
There were more than two people at the house and Oatho told the two people on the other side when he came up stairs to the attic the its able to be separated and he also said to pick it up gently
How do they get the sections through the attic door? The model is too detailed for everything to be secured down tightly enough to not fall off. They would have to tilt the sections sideways, which would knock off parts of the model.