“Never believe that anti-Semites are completely unaware of the absurdity of their replies. They know that their remarks are frivolous, open to challenge. But they are amusing themselves, for it is their adversary who is obliged to use words responsibly, since he believes in words. The anti-Semites have the right to play. They even like to play with discourse for, by giving ridiculous reasons, they discredit the seriousness of their interlocutors. They delight in acting in bad faith, since they seek not to persuade by sound argument but to intimidate and disconcert. If you press them too closely, they will abruptly fall silent, loftily indicating by some phrase that the time for argument is past.”

When you do stuff like this all you are doing is giving them a platform, letting them do PR for their hideous causes. They can calmly discuss the very existence of a group of people and then exit when it suits them. A member of that group is, rightfully, unlikely to have that sort of calm intellectual distance from a conversation about their right to exist.