I think you're confusing "troll" and "bully."
A troll is just someone who wants chaos and subverted attention.
Some of the worst bullying, however, is done completely in private, person-to-person, where the bully intimidates the victim into not telling anyone what said bully is up to.
Casting light on this sort of bully, much like casting light on an infected wound, can aid in clearing out the problem. If anything, it subverts the shame (rightfully) onto the bully, for participation in such cruel and underhanded intimidation tactics that would never be acceptable in public.
On the contrary, if you stay silent about the bully, you're giving said bully free licence to carry on pushing around other people. Even if your own personal mind is above it to where it lends the bully no room, not everybody is yet as strong as that. Those are the people the anchorwoman in question is concerned for, and that's why she rightfully exposed the idiot for what he is, on local television.