This all seems correct, I'll just add another facet, which for all I know you've already considered or addressed anywhere, but in any case: when you vote, you're in a private booth voting in secret. So it's not clear that this expresses anything about helping people. I could be in there voting for the "Help People Party" or for the "Be Horrible Party"; no one knows. I could go into the book and abstain! The only thing I'm "expressing" by going to the booth is "I am a voter," from which I suppose you could also infer "I believe in democracy," or, less charitably, "I believe that if enough other people agree with me, it's ok to force others to do what I say." But as to whether I support Smith versus Jones, the bumper sticker or yard sign is far more expressive than the vote I may or may not be casting.
This all seems correct, I'll just add another facet, which for all I know you've already considered or addressed anywhere, but in any case: when you vote, you're in a private booth voting in secret. So it's not clear that this expresses anything about helping people. I could be in there voting for the "Help People Party" or for the "Be Horrible Party"; no one knows. I could go into the book and abstain! The only thing I'm "expressing" by going to the booth is "I am a voter," from which I suppose you could also infer "I believe in democracy," or, less charitably, "I believe that if enough other people agree with me, it's ok to force others to do what I say." But as to whether I support Smith versus Jones, the bumper sticker or yard sign is far more expressive than the vote I may or may not be casting.