The bias here, of course is the "allegedly anti-Semitic" description of the balloon. You may say, "of course they should describe it as alleged, it hasn't been proven in a court of law!" And that is certainly true, but it speaks to the consistency of the Huffington Post that any time something allegedly against Jews appears, it is described as exactly that. In contrast, when ads are accused of being Islamophobic, the Huffington Post prints those accusations as fact. Apparently the double standards remain.
Anyway, the Huffington Post readership reacted exactly as they have been primed to. I don't care so much about those defending Waters by claiming that he is against all religions (though no sign of a pig with a star and crescent on it) or that it has to do with his show. You see the anti-Semites of the Huffington Post did a great job proving that this isn't anti-Semitic by bashing Israel and its "Zionists" supporters, and favoriting each other:
They haven't fought the war anti-Semitism for a while, I guess they were itching to fight again.