How would you describe, say, the movement that won independence for India? Or ended apartheid in South Africa? Or brought forms of democracy to most of Latin America? (I leave aside the more general victory of movements for national independence, since you might want to argue that they didn't result in bourgeois-democratic forms of government).
Surely what's wrong with the Stalinist theory is not that it allows for the empirical judgement that 'the bourgeoisie' can lead a bourgeois democratic movement/revolution, but that it proposes that it *will* do so, and - much worse - that the working class should subordinate itself to the bourgeoisie, should not push its own interests for fear of breaking up the 'bloc of four classes' (or whatever).
There is a democratic revolution in Libya. Broadly speaking the forces leading it are bourgeois. This is just an empirical statement, not a recommendation.