Auschwitz Lines

Sarah Stern in The New Republic explains that Israel can't make peace with the Palestinians because of the "maximalist Palestinian position" which I was expecting to see described as the destruction of Israel, but which actually turns out to be reasonably characterized as "an Israeli retreat to the pre-1967 borders, which are actually the 1949 armistice lines." So why not make a deal like that? "These boundaries were nine miles wide at their narrowest point, lacking the strategic depth to enable Israel to defend itself, which led the former Israeli Ambassador to the United Nations, Abba Eban (of the Labour Party) to dub them 'the Auschwitz lines.'"

Okay, but given that the '49 armistice was the result of an actual war, the lines can't have been all that indefensible. What's more, the lines were successfully defending in 1967. And Israel's conventional military superiority vis-a-vis its neighbors has grown larger. And now Israel has nuclear weapons! What's more, Israel now has peace agreements with Jordan and Egypt. If non-nuclear Israel could defend the '67 borders against Egypt, Jordan, and Syria combined surely it can defend them now against Syria alone with the help of its nuclear weapons.