Well, yes, sort of. Threatening to murder a public figure (or worse, murdering) is terrorism in the way that it discourages others to become public figures. Which in turn gnaws on a certain foundation of democracy, which is that everyone should be able to hold public office without fear of violence.
If we don't protect that foundation, only the people whose supporters are doing the threatening will eventually hold public office.
If we don't protect that foundation, only the people whose supporters are doing the threatening will eventually hold public office.