Argh, reading about 'rice resin' and 'corn plastic'... I'm not a fan of calling polymers by their source material. You won't call PP, PS, PE, PET, etc. 'dug-up dinosaur juice plastic' for a reason.
Yeah, I don't think they need to specify the source unless they are trying to emphasize that it's NOT from fossil oil (for those who want to avoid that).