Jason's attempts to reconcile decent instincts with a slavish commitment to orthodox "Trotskyist" dogma are becoming difficult to watch. Are you seriously suggesting that "racist police off our streets" would be your banner-headline response to the police intervening to stop fascists beating up or killing a black or Asian person? Of course it wouldn't. "Racist police off our streets" might be your general framing perspective but you don't just robotically raise one formulaic slogan ("racist police off our streets", or indeed "no to imperialist intervention!") in every situation; you assess reality, you assess the actual balance of forces and you assess, depending on those assessments, what implications that slogan actually has in a concrete situation. The only possible implication of "no to imperialist intervention" as a banner-headline slogan in the context of Libya, right now (rather than Libya through the lens of some ortho-Trot "anti-imperialist" fantasy) is "victory to Qaddafi".
It's telling that Jason says "Do we say UK, US, French (imperialist) planes and bombs out of Libya?", but later says his position is to demand that imperialist states arm the rebels. Notice that the word "imperialist" is in parentheses in the first sentence. Presumably that's because Jason thinks that the planes and bombs would somehow be less "imperialist" if they were given to the rebels rather than used by UK, US and France themselves. This simply isn't the case; whether they're using them directly or giving them to rebels, "UK, US and French planes and bombs" in Libya is "imperialist intervention". You can't say "no to imperialist intervention" and "arm the rebels"; the two slogans are directly, mutually exclusive and contradictory.
And to David, if for you the main, overarching concern here is not to give "a boost" to the idea of "liberal intervention", presumably you'd counsel the Libyan rebels not to take politico-military advantage of any openings or opportunities created by the weakening of Qaddafi's forces, in case that gave "a boost" to the idea of "liberal intervention". Applying the logic of your position to Iraq in 2003 you'd also have to tell Iraqi workers not to organise, because to do so would give "a boost" to the same idea by highlighting how opportunities to organise existed that didn't exist before the invasion.
The question for us isn't the ideological esteem in which particular abstract notions are held; the question is the balance of class forces. In Iraq, we could reasonably assess that despite the likely positive side-effects of the toppling of the Ba'athist regime (which were not insignificant), a full-scale imperialist invasion of Iraq was a clear, direct threat to Iraqi self-determination which "outweighed" (if you want to be cold and calculating about it) the other concerns. In Libya, the threat posed by Qaddafi to a social upheaval going on right now outweighs the concern that the idea of liberal intervention might get a boost (amongst whom, by the way?). Is the massacre of the Libyan uprising by a brutal Stalinoid dictator a price you're willing to pay to keep the "distrust that millions of [unnamed, unspecified] people feel towards imperialism" nice and "healthy"? Maybe it is, but in that case I suggest that your political point of departure is not the advancement of working-class or even democratic struggle but rather an abstract notion of "anti-imperialism". If we have completely different starting points then this debate is going to become increasingly difficult to have.