I'll take the more libertarian stance and instead of trying to have it enforced I'l simply not help or respond to people with an annoying avatar.
Wouldn't the libertarian stance really be to just get over it, or block it yourself?
Refusing to help someone because of their decisions is more of a Dicko-anarchistic (pun alert) stance.
Anarcho-penis, maybe?
Both are valid options, blocking the annoying image, or ostracizing the owner of it, but given the ease of blocking the image, I'd recommend that as the "politic" thing to do.