Yoplait containers endanger squirrels

There seems to be a recent rash of small animals getting their heads stuck in yogurt containers (if YouTube is to be believed, at least) and many are calling for a boycott of Yoplait until General Mills changes the design. Apparently, GM redesigned the Yoplait yogurt cups a decade ago in response to animal-rights activists who were concerned about skunks getting stuck in them. A note on the package asks consumers to crush the cups before disposal, but should GM take more responsibilities for the dangers its packaging poses to animals, or do we blame littering yogurt eaters?