To be a neocon you have to hate him. Imply he's a Nazi, accuse him of "flirting with Fascism", rejoice that he's leading the kooks and the tinfoil hatters out of the newly purified GOP.
You need to froth at the mouth a bit. Denounce him as a humourless hatemonger. A racist xenophobic isolationist. Simply disagreeing just won't do. You won't get invited to the best parties that way.