Whats to stop innocent peoples details being posted by malicious users?

A few months ago I picked up a child who had fallen over in the playground and seemed to be being ignored by all the adults there, and then got a torrent of abuse form the childs 'mother', including being called a paedo, just for being caring and kind! It was unkind and hurtful to me, but my kids were horrified at her and appalled by her language. I'd hate for my name to end up on a list because of people like this!