Not sure if I’d want to pull his daughter into this mess but in general answering with an equally faked video would be a genius marketing stunt. Maybe a video where Elon writes ‘I must not share manipulated videos’ to a chalk board like Bart in the Simpsons.
I only ever used it for 3D printing but FreeCAD apparantly also has a floor plan functionality. I found this video that might give you some insights on how it looks: https://www.youtube.com/watch?v=WMk7pdnEnXM
When using FreeCAD for 3D printing, you don’t necessarily have to add measures/constraints to everything, so I’d assume it’s similar here.