"The material they show in the article is massive. Thick, long and heavy. Even if there are kilns big enough, the wood would no longer be straight after a fast kiln drying."
This is not true, depending on timeline.
It's true of the production rate kilns, and as you say, it doesn't matter for construction lumber, which is why they do it.
But assuming 3+ years to dry your 3x3" board, even doing it in a kiln at a 6 month rate (or whatever) would be a vast improvement, and would basically not bow or check. Again, there is actually a vast amount of research on drying schedules vs defects and how to optimize for whatever you want for a given wood species.
As for kiln size, again, solar kilns are quite trivial to build for basically any size or shape, and can easily be temperature controlled for something like this.
(and they could easily build a kiln in the space they have shown in that article)
To whit: I've built a solar kiln in maryland for 30+ ft boards before, and cost of materials was < $1000.
(I used to buy lumber from a guy who was responsible for handling downed trees for some cities in northern virginia, and he used to saw and sell the lumber. He did the nail removal, etc)
"Even if the wood was kiln dried, it would still have to acclimatizate for months or years before it would be at a stable 13% humidity of San Francisco."
Why? You can just stop drying it at 13% (instead of the 7-8% that is normal).