It's a capitulation in the face of the capitalist powers in the developed regions of global capitalism and a fetishism of guerrillaism. Third Worldists don't believe that there is a proletariat in the 'west' instead believing that there are only labour aristocrats, which is basically an abuse of the term, and so they don't believe that a revolution is possible in the centres of capitalist power. They laud guerilla formations wherever they crop up in the less developed regions of global capitalism, especially if they wave the red flag in defiance of imperialism. But this all amounts to basically ignoring the centres of imperialism and the power workers could have in the developed regions to end imperialism by toppling the imperialist powers. It's ultimately an abandonment of marxism.