"propaganda?" the whole point of the movie was about how hatred consumed him and how that hatred had destructive consequences for his life and family. If it had a stance it was anti-hate anti-violence.
Yes. And that message was propaganda-laden. The movie posited that all of his hate was born of conservative ideals and anti-socialist tendencies.
When he gets out of prison, it's not just the hate he loses. All of his opinions change. It outright stated that one lead to the other.
i disagree with your interpretation of the movie. But to be fair I only saw it once when it came out. So my memory may not be 100% accurate on any political messages, but I don't remember anything other than hatred as the core theme.