The debate was about one side calling it hate speech and the other side defending it as a first amendment right. It appeared in pristine Lefty heaven, San Francisco, because the people behind it won a lawsuit in New York.
I do not believe this has anything to do with the first amendment. I think people who consider it a First Amendment issue are morally degenerate.
This is a clear-cut statement that you either agree with or you are not civilized. The Palestinians in both the West Bank and Gaza gleefully murder innocent civilians in Israel. That is savage. That is not acceptable to civilized people.
You do not need first amendment protection to recognize the immoral, disgusting, uncivilized behavior of the Palestinian people.
The only argument I can imagine, an extreme argument, is that not all Palestinians support this uncivilized savage behavior. Unfortunately for that argument there is not a single outspoken opponent in the entire Palestinian world that opposes their savage behavior. Not one.
Therefore this imaginary argument has no validity.
Back to the core issue. This bus sign does not raise any First Amendment issues. It only raises the issues of who is civilized. Most San Franciscans really aren't.