"Beyond that, I think leftists should try to find out more about Islam in all its varieties, Muslims of all kinds, predominantly Muslim nations (with a wide variety of customs, class structures, economic situations, balances of political forces, intellectual trends, etc.) and see if they can't find things they like about them."
It'd be nice if everyone did that, not just leftists. On the one hand they might find Islam as a written, revealed religion -- that is, the Qur'an and Hadiths -- are extremely similar to Christianity and Judaism. An Abrahamic faith with a lot of the same stories and just as many prescriptions for behavior that are either very bizarre or don't make sense for our times, and some good stuff that you can cherry pick out of the whole and focus laserlike on, ignoring the rest.
No one religion has a monopoly on spawning odious groups of violent & coercive people. Christianity has succeeded in that department. It doesn't make sense to focus on one Abrahmic faith, Islam, while ignoring the other two Abrahamic faiths.
On the other hand, the "enemy of my enemy is my friend" strategy is a little too disingenuous and Machiavellian for my tastes. I don't feel the need to ally with some large power unit simply because it 8s a power unit or represents some viable counter-power to something I'm opposed. There are several in the world to choose from: Chave-ian Latin American socialism is one. Iran, or more specifically what's being referred to as "leftist Islam" (maybe wishfully in a lot of cases) is another. I'm not sure I want to throw my lot in with either counter-power. There are principles I think are worth are worth supporting, but allying with something because it's simply powerful seems pretty warped.
-B.