What are you astonished by? Do you think lethal force in self defense against law enforcement is justified, even when the police are conducting a lawful arrest?

Let's say someone robs a liquor store at gunpoint. The police chase him down, with their guns drawn - which is totally reasonable given that they're trying to arrest a criminal who is armed with a gun. The robber turns and sees a pair of police officers with their guns trained on him. The robber shots the two cops dead.

Is this a justified shooting? By your logic, yes it is. The robber saw two police officers with their guns drawn, that meets your criteria for the law enforcement officers presenting a deadly threat.

On my end, I absolutely am astonished by your attempts to justify shooting law enforcement officers.