So far, so not-really-surprising. The Iranians aren't about to harm the US in any direct way, so it's easier to be indulgent if there's no real danger. If you follow the article closely, however, you'll see that's not the only distinction between the camps.
The other left-wing pro-Israel groups arrived at their Iran policies partly
because of their alliance with an array of liberal Democrats wary of engaging
Iran in the wake of the Iraq War and its resultant quagmire. Behind the scenes,
these groups have sought sanctions that would not harm ordinary Iranians.
Translation: If you're on the Left of American politics, you cannot see the Iranian challenge on its own merits. Like it or not, you see it through the prism of American involvement in Iraq. Whether this is relevant to Israel's existence is moot, but that's life.