Gilad Atzmon is a fringe anti-Semitic thinker, who spends much of his time savaging Jews for alleged schemes of world-domination and racist parochialism. For the most part, he owns this identity (calling himself, among other things, a "proud self-hating Jew"), but occasionally he tries to kick up some dust around it. One way he does this is by saying that when he attacks "Jewishness", he isn't referring to all Jews per se but rather a style of thinking or behavior that is wrong or immoral, which may be done by Jews or non-Jews (so, for example, he might say George W. Bush is behaving Jewishly). It's not a good faith argument (Atzmon's argument is more or less far-right hyper-colorblindness and his definition of "Jewishness" is anyone who maintains any sort of group identity. But he doesn't apply this "standard" universally, only to persons he dislikes), but even taken on its face it'd still be anti-Semitic -- using "Jew" as a pejorative is inherently hostile to that group "even if" one means to encompass non-Jews under its ambit (compare calling someone a "Jew" because they're allegedly cheap).
It's no shock to anyone that Robert Spencer is a racist bigot against Muslims. But his latest column might as well be taken from the Gilad Atzmon playbook, asking whether New York mayor Michael Bloomberg "is secretly a Muslim". Now, Spencer agrees that obviously Bloomberg isn't literally a Muslim. But, he says, by taking authoritarian actions (Spencer is referring to the big soda ban, rather than something like, I don't know, barring minority religious practices), he's basically "acting" Muslim. "Muslim" is a referent not to Muslims, necessarily, but to a class of behavior that Spencer finds distasteful (which he imputes to the vast majority of all Muslims but also to basically anyone else he disagrees with). That behavior is then transmuted into a sort of totalitarian impulse that desires to squelch liberty and dominate the world. So it's basically Gilad Atzmon with a new label. He can't even distinguish himself based on target profile -- after all, Spencer's targeting Jews too (who -- though probably not supporting soda bans -- tend towards the sort of liberalism that Spencer has painted a target over).
This isn't really all that surprising -- bromides about haters being haters aside, polling indicates that the best predictor of anti-Muslim sentiment is anti-Jewish sentiment. Spencer is just another practitioner of far-right hatred that, while casting itself as Islamophobic, really has its sights on essentially any minority group.