I think it's always a good etiquette, not only on this forum but elsewhere too, that one is held accountable for his statements, remarks or opinion. One should not be allowed to just come in, drop an unsubstantiated and controversial bomb, and get away with it. Of course everyone is entitled to his opinion, which also means that everyone else is also entitled to his opinion against that OP's opinion. As long as the opinion is delivered not in a derogatory manner or smacks of racial or religious bigotry, I guess the forum is always a level playing field.
I always hold to that age-old maxim - be prepared to receive as good as what you dish out. If you want to live by the sword, then don't chicken out of dying by the sword too. Don't use youthful foolishness or novice ignorance as an excuse.