but didn't they allude to it throughout the entire film? the reason for the food scarcity, and then mumble getting blamed for it as some kind of religious omen, the skua who got "abducted", the crane causing that avalanche...ect. the movie was obviously building up to something involving the human effect on Antarctica, so that was its natural climax, and the whole message didn't take a back seat to the 'save the environment' one, mumble, by "being himself" as you put it, drew the humans attention to their actions, saving emperor land or whatever the penguins called their home.