1) "the AWL thinks that a mass opposition in the UK to the imperialist adventures of the government in Libya would be a bad thing"
We don't think that. We're in favour of that. The thing is, opposition to imperialist adventures in Libya does not mean opposing every single specific action of the government in Libya. For sure - we should *mistrust* every single specific action of the government in Libya, understand the cynical motivations behind it, etc. etc. - but there's no reason to call specifically for the immediate end of an action which is obviously stopping the rebels from being massacred.
2) On the thing of the idea of humanitarian intervention getting a knock vs. the Libyan rebels being massacred - I think that there are better ways of making propaganda against liberal intervention which don't involve allowing the rebels to be massacred in order to make a point. I also think that bone-headed, negative-imprint opposition to every specific action of imperialism is not a policy which is going to give people confidence in your politics. If you're out there raising slogans whose logical end is obviously the destruction of the rebels in Libya then people will either think that your slogans are badly wrong - or that you don't take them seriously enough to think through their implications if they were applied to the real world.
3) "The reason people do oppose it (some polls have said the majority of people in the UK do as it goes), is because they know it is for entirely cynical reasons." I think there are various reasons why people don't support it. I think cynicism with imperialism is probably not the majority reason - it strikes me as far more likely to be a sort of nationalist-isolationist sentiment.