From the article it does sound like this one may actually be biodegradable, the other implementations I’ve seen involve stripping lignin from the wood and impregnating it with resin, which all hair-splitting aside is basically plastic with extra steps. This is apparently using egg whites and some kind of rice extract instead of resin, so I don’t see any reason this shouldn’t be biodegradable.

Suitability for production and practical applications remain to be seen though.