I can prove that this is an Urban Legend. 
Here are my points :
If you look at the photos of the chopsticks left in the bottle
in the fridge and then the contents of the bottle as it's being
removed from the fridge, you'll see that the pieces in the bottle
are no longer of uniform sticks and there are actually shapes and
sizes that aren't congruent with the cut-up chopsticks.
Note how flat the pieces look... soaking wood will never
'flatten' them, if anything, soaked wood swells up and the fibres
at the end start to come unravelled, that's just how wood behaves
when soaked in water for a period of time. It can never lay
completely limp, as shown in the photo where a piece of 'bamboo
shoot' is being picked up by a pair of chopsticks. I mean,
have you ever seen wood that's THAT supple / flexible?
On top of that, no amount of soaking / marinating can tenderise
wood fibres to the extent that they are totally undetectable to the
human palate.
A rudimentary knowledge of cooking will also tell you that for a
marinade that's dark brown in colour (note colour of marinade when
bottle is put into fridge), the contents will be 'stained' a darker
shade as well, and not end up lighter in colour! 
Besides, the cost of using disposable chopsticks to make bamboo
shoots is probably much higher than to just purchase bamboo shoots
in the first place. I think bamboo shoots as an ingredient,
is still cheaper, so it doesn't make economic sense to resort to
this.
So... does all that dispel the myth? 
thing is, in China, real food is getting scarce... cardboard
processed used to be more expensive compared to pork..
not anymore..
this, on the other hand, is cheaper than bamboo shoots.. which
has to be harvested..
besides, i won't put anything past the idiots in PRC.. Mao
destroyed any morality in them..
btw.. i went to Giant a while ago.. guess what? no bamboo shoot
available!!
