The point that Sunfish makes is that it's really easy for one bad apple to spoilt the bunch. Do you think that it matters to the average non-aviation member of the public that the person attacking Olivia, Alan and the rest; and using patronising, insulting language about pax may not in fact be a QF pilot?
Should a punter see some of this, what they may see, or perceive is a professional pilot sitting atop a pedestal calling them (the punter) uneducated, ignorant and/or stupid. They also see the same professional pilot defending PIA, bagging QF management, and they may make a link - correct or otherwise. Never mind that the poster in question works for JQ or Virgin or in GA or sits at a desk playing flight sims - in the mind of the punter, the difference may not be there.
Remember, it's not what people say, it's what the other people hear that's important.