About this part of your comment please understand that making suggestions or posting ideas about how to improve wordpress.com could improve should be done in the "Ideas Forum" or by contacting Staff directly.
If I may leave a suggestion: you might think of broader privacy settings, because there really is nothing a person can do against unbalanced people.
As for this part of your comment:
…I kind of wonder what your role really is here...
Please understand that this is for the most part a peer to peer technical support forum. That means most of the folk who answer questions here are your fellow bloggers: we are volunteers. As such we truly do try the best we can to be useful. Please be kind!
I understand that you are upset, and having someone continuously making negative comments is not pleasant. You came here hoping for help putting a stop to it. The people who have told you about your practical and effective options.
If you have other questions, please don't hesitate to come to these forums to find help. While not all answers can be clear-cut and pleasing, we do provide quite a bit of useful information…