The material conditions did change significantly with the destruction of the Death Star, as it’s destruction created an insane economic vacuum, power vacuum, military leadership vacuum, and undermined the entire doctrinal approach of the Empire. Plus while it is a Anarchist Theory, there is a little merit to the “Propaganda of the Deed” as an unintentional consequence of revolutionary action.

Further, major turning points in a war don’t instantly end it, just like how the killing of the tsar didn’t instantly end the Russian civil war. The Bolsheviks didn’t get to just clap their hands and say “Yay! The dictator is dead! War over!” Plus the emperor wasn’t even on the Death Star.