'Perceived behaviour' such as revealing where she lived ? I don't blame her for being angry. Anyone who remains silent while a pensioner who lives by herself is threatened in that way is exactly what Brenda called them.
Did "Mod" (who would presumably have witnessed Brenda's own vile outing attempts and insults directed to another twitter user) know a) she was a pensioner and b) that she lived by herself? Presumably you can understand why McCann supporters get angry when people they support and they themselves are threatened and intimidated too then, (which is just about all of them, from what I've seen).
That #McCann tag is ALL about threats and insults, I think you'd struggle to name anyone who posts on there regularly who hasn't been threatened, abused, called a paedo, been outed, received threats, and I'm talking about both sides here - it really is shitter on Twitter and why anyone puts themselves through that on a daily basis beats me. They obviously enjoy the abuse - both giving and receiving.