The size and extravagance of this thing is rather off-putting. I was expecting a modest off grid passive house.
I dunno, maybe my thought is unrealistic - but if I were to splash out a ton of money for a palatial rural manse, I'd shoot for something with a bit more space than a large-ish suburban home.
Especially because one of the most common uses of such a property is entertainment - forget having folks stay over unless you make the kids bunk?
So how are they going to be entertaining people all the time (they specifically mention entertaining large groups being important to them)? Come over for an evening, except one of you can't drink and has to drive 2 hours back at the end of the night??
At a bare minimum it needs to be large enough to have a guest suite - the central socializing spaces like the kitchen and living room also need to be scaled for that use.
Ideally (assuming a grand budget) you can have separate structures for guests entirely.
But certainly one has to assume that guests are bunking over, given how remote the location is. It seems eminently unreasonable to assume guests are driving several hours at the end of the evening.