Guillow is not the only company that is having trouble getting good quality balsa. A couple of natural gas tankers are under construction, which always hits the world supply of top quality balsa hard, (I wonder what they do with all that high-grade balsa when they scrap one of those things?), and the Chinese are buying up the balsa plantations in Central America.
Why the Chinese are doing this is a good question. I think, as in other places in the world, it's going into other uses than models, like the cushion layer in laminated flooring. I know that many of the ARFs are made in China, but they can't be making that many, can they?
Anyway, the model manufacturers, here and in the EU are the hardest hit by the shortage. They are even looking at sources in Asia. (I guess someone took some seedlings and started plantations in Indonesia.) Shipments of what was supposed to be 10 pound wood has been coming in at between 13 and 24 pounds. The stuff that is coming in at 10 pounds or under is a bit crumbly. This puts all the model kit manufacturers in a bind. Do they put out kits with heavy wood, light wood that is difficult to build with because it is fragile, or nothing at all? If this keeps up, we stick and tissue builders may be back to pine or basswood and cardboard like in WWII although some models of that era flew amazingly well.