It will be news to Israel's rulers that Syria's support for Hezbollah is actually on behalf of the Zionist state.
It seems to me that on Syria, your position will ultimately come down to how much importance you put on Israel/Palestine. If you believe opposition to Zionism is a paramount duty of the left, then it's hard to see how you can support more anarchy, ethnic cleansing, and Western/Israeli/Saudi military intervention in the region. Especially since Iraq is still smoldering from a decade of what could be fairly called genocide. On the other hand, if Israel and the occupation is just one struggle out of many and not inherently more important than Syria, Libya, Paraguay, what have you, then fine. It might make sense to break bread with the enemy of your enemy and support the motley crew of Syrian rebels.
But, honestly, it's a bit disingenuous of Western Marxists to criticize foreign regimes as not being progressive. At this point, in 2012, which force is progressive? I suspect Shane that you'd say no government in the world today is. Well, what's the point in making the distinction then?