I don't believe the shorting is based on company value per se....

I don't believe the shorting is based on company value per se. Look at the sector prices. GXY is actually just in the middle of the pack of price falls. Not just the sector here either, it is happening across stock markets.
I suspect that the lack of an official market, and the BS about China spot prices falling is behind all this (although oil companies aren't upset by it I'm sure).
Lithium pricing is poorly understood by the market, and I think the insto shorters are just taking advantage of the opportunity.