I had not even clicked on the link when I posted it, just noticed a 3d printing sustainability claim at the info box. After doing a very minor amount of research I would agree that PLA filament looks like a much more sustainable product than PETG. With biodegradable polymers the potential for biodegradation is much higher based on the relative amount of oxygen in the monomer (the repeating unit which makes up the polymer). The oxygens kind of acts like a handle at the molecular level allowing a chemical attack to grab hold.
Polylactic acid is composed of repeating units of lactic acid. It is available from a renewable biostock as Pierre pointed out, and it degrades into harmless byproducts.
Polyethylene terephthalate’s monomer is ethylene terephthalate. It’s synthesis involves much harsher chemicals, and has raised concerns about its potential activity as an endocrine disruptor. Based on the structure I would also say that under combustion it very likely produces a whole host of carcinogens.
To sum it up I would call bullshit on this kickstarter, this appears to be a clear case of greenwashing. I just wish that the 3 people that have contributed $2500 since I first posted the link knew that…