Yep, and by the person saying something hateful and threatening, not by the people who feel unsafe.

Thanks for making this explicit. I should have.

In my limited experience, shunning is more visible than heckling.

Interesting. What kind of shunning are you thinking of? Because my guess would be that shunning would be less visible (if it were accomplished by not showing up at a specific event). It might be more of a powerful statement though, depending on who was paying attention.