This is the part you simply do not understand. You are wrong; dead wrong.
Harassment is not speech at all. It is conduct. Harassment requires repeated unwanted contact. There is no evidence that there is repeated contact at all from the article. There is no evidence anyone has been informed that their contact is unwanted at all. There is no harassment in this matter despite the usage of the word in the article.
"True threats" are not Free Speech. There is no evidence at all that the Idaho electors have faced any "true threats". In fact, one Idaho elector said that the contact isn't even intimidating.