It’s a bit different when the propaganda is aimed directly at children who have so little discernment. Bruce Dern’s character in Silent Running was for an adult audience of SciFi folks, and they generally have some degree of discernment with which to reject propaganda. Children just soak it up and incorporate it into their world view ... and that’s precisely why lieberals make movies like Wall-E and Happy Feet.
People who were surprised by ‘Happy Feet’ should’ve been aware of who made a film. Australian filmmaker George Miller is known for the pessimistic ‘Mad Max’ films and ‘Baby: Pig in the City’ which was another children’s film most people found too disturbing.