Of course, if they had waited enough years, nature would have done to the billboard what it did to Grossinger's in New York:
If you’re the kind of person that’s inclined to spend their vacation somewhere dark, dusty, and dangerous, the motto still rings true today, and you’re not coming for the five-star kosher kitchen. For just as quickly as the resort prospered into a world-class institution, it’s descended into a swift decay. Explorers frequent the grounds, armed with cameras in an attempt to capture the beauty in its devastation, sifting through the artifacts—a broken lounge chair, old reservation records—piecing together a lost age of tourism.
Every single person in that video seemed like a parody of the negative LA stereotype, and the writing seemed like a parody of bad lefty-talk, and the science is bad, and the idea itself is absurd, so... This whole thing is a joke, right? I have to assume it is, and sort of a mean spirited joke at that. I could see this turning out to be a piece of right-wing performance art.
Bamboo - especially giant timber bamboo, which this looks to be - is not an epiphyte, so it's going to need fairly intensive maintenance to keep it alive over time. Any contained bamboo is going to become root-bound, so nutrients will be a problem. Better to choose a species that thrives in the forest canopy rather than giant timber bamboo, whose dead 50-60 foot tall canes don't decompose readily and will eventually come crashing down on their surroundings.
Of course, if they had waited enough years, nature would have done to the billboard what it did to Grossinger's in New York:
http://abandonednyc.com/2012/11/11/check…
http://www.kickstarter.com/projects/1045…