It seems to me that you believe that there is no support from the GM's...
The best you can do against OOC harassment is to tell the person OOC'ly to stop it and to leave you alone. If they don't you will have all the support from the GM's.
I wish.
It also seems to me that you are suffering such at the moment? - I say this by the very fact that you are so adamant that the problem is that bad.
If you are - Have you reported it? If not - why not?
As to the game having mechanics to stop such - you will never (As I have already stated) stop it happening, you can only dissuade it by your own actions.
Bilbous was not simplistic about it - his words were quite true, and on topic. Harassment is not just in game - it can start outside the game and migrate to it, which is exactly what you were stating in the first place
As others have complained from time to time, it isn't unheard of for people to express out of game hatreds through actions that they try to pass as being in character.
The ooc has to start somewhere, and for sure - as stated by Bilbous, it could very well stem from peoples reactions to someones behaviour or oppinions here on the forums. I don't think he was stating that 'people who suffer from this kind of griefing tend to deserve it' at all. Having an oppinion does not make you deserving of such griefing.
There will always be those who are bitter and twisted because they don't like their lot in life, or they cannot come to terms with the fact that others have different appinions to them and wont side with them, so they turn to 'bully tactics'. And some are just doing it for the reaction - so reacting to it just perpetuates their behaviour.
Sadly - REPORTING and IGNORING are the only tools available to deal with such behaviour, and by not doing such behaviour yourself in a clear and transparant way - any mud slung won't stick for long, as gamers will soon see by playing with you what you are actually like.
GM's are there to help the community police this behaviour.