He knows the difference but hates Israel so much he wishes the numbers were reversed. Or that someone had already taken out Israel.
He was and is a communist. The first deep plant Soviet sympathizer who got to the Presidency.
Regrettably, you are correct. Very few Americans will candidly admit to their being in the throes of anti-Semitism--it is usually camouflaged as "anti-Zionism," or a mere political difference with Israel's current leadership, or...well, something. Anything. But never what it really is.
Carter strikes me as anti-Semitic to the core. He just lacks the integrity or moral courage to express his core convictions unabashedly.