I think this is exactly the question at stake. It doesn't matter what we (leftists) say in the short term. It's not as though Obama and his generals are waiting on the "go-ahead" from LBO-talk or Marxmail to stage an intervention. Or rather I should say, it always *matters* what we say, but it's not going to affect the short-run military action.
What we say does matter in the long haul, and here's why: If we all get behind intervention this time around (for BS humanitarian reasons, etc.) then we are providing political cover for such actions. It should be our role to play the "knee jerk anti-imperialist" but this, of course, doesn't mean to defend any fool who stands up against the West.
This is a case of the U.S. trying to reassert itself and re-establish its neoliberal client regimes. This was made crystal clear when NATO coerced the rebels into continuing Gaddafi's oil and trade agreements in the event he would be deposed in the offensive.
What we say in the long run *does* matter if you consider yourself to be anti-capitalist and against the cruelty of neoliberalism. But don't kid yourself--the short run was all planned out weeks ago, without our help, for sure.