Seth is a right-wing voice, and right-wing voices love Israeli settlements. Primarily because Israeli settlers are also right-wing voices...
However, while you can label Jews opposed to the settlements as anti-Zionist, it's kind of silly to try and label them as anti-Semitic. Anti-semite implies hatred of people for being Jewish, which becomes ludicrous when you try to claim Jews hate other Jews. That's like claiming that because I oppose Trump and many conservative causes in general I somehow hate "conservatives". However, I have many friends and esp family who qualify as "conservative" and I don't begin to hate them...
Pretty sure Seth KNOWS all this, he's a wingnut, but he's not devoid of intelligence. He also knows that low info voters/others he's trying to influence are probably not going to get as inflamed over him referring to BJ as anti-Zionist (a political distinction that includes both Jews and non-Jews) as they will if he calls them anti-Semite, an attempt to label them racist (which really is only possible for people who are not Semites themselves). It's all political posturing...