The broader meaning of propaganda then just means "spreading ideas to further a cause". If that's true then it would be a neutral word. But "propaganda" is not

The broader meaning of propaganda then just means "spreading ideas to further a cause". If that's true then it would be a neutral word. But "propaganda" is not a neutral word in practice. It implies something intentionally misleading. I don't think expressing concern about Hamas is propaganda. If the billboard said (or implied) "all Palestinians are Hamas terrorists" that would be propaganda