Sig isn't alone. There is apparently a world wide allocation problem with balsa wood. If you google "balsa wood shortage" you'll pull up a myriad of different descriptions and explanations ranging from increases for industrial demand, labor shortages, harvesting problems, etc.

Sig is unique in that they don't offer much in the way of non-balsa models. Giant scale stuff is normally all light plywood and electric aircraft are often made of foam.

One of the reasons for the recent push of EDF models might simply be due to the manufacturers' ability to supply them. Notice that Nitro Planes is sold out of most of their balsa ARFs, but they seem to have an endless supply RTF and ATF EDF and other foamy electric planes.

Thunder Tiger went to far as to start purchasing other product lines, buying a giant scale manufacturer last year and then recently acquiring the ModelFly line of plastic ARFs like their new Cessna Cardinal and Ready Mk3 trainer ARFs.

Great Planes and Hangar 9 have been thinning their product lines. Global Hobby is heavily emphasizing VQ ARFs and many new Horizon ARFs are from Seagull rather than Hangar 9. My guess is that Vietnamese manufacturers get preferential access to balsa supplies, and they're the only ones able to ship new product.

If Sig can't get the wood they need to make their product, they'll need to get creative to stay in the game.