Interesting discussion:-).
Im sure natives could control checking and drying just fine (even without an attic;-). I also dont buy the "prevent rot" explanation (yet), since we have allready established that osage can survive for decades as fence posts and still make perfectly good bows. As for seasoning I have yet to see any tangible proof, that seasoned staves make better bows (better as in, worth the effort of seasoning).
This pretty much leaves storage. Im thinking water/mud storage would only make sense for a people that migrates. Unprocessed bow staves would be hell to travel with for people with a nomadic lifestyle, but can be stored mores easily than in a bog, if the settlement was permanent.
But I admit that, that is really just pushing the problem ahead....submerged staves will still have to be dried, and it will take as long when retrived from water, as it would when the wood was green.
Alternativly the "water curing" does something to the wood that eases the work of turning it into a bow. I dont think partial rot (rot of the sapwood only) is it....submerged wood last forever almost. Bug prevention is a possibility....but dont you just push the problem ahead?....I mean, the staves still have to be dried and thus the bug issue returns.
Just my thoughts on the subject;-)
Cheers