Chap and Abaddon, more to Abbadon though since you seem to have sympathy for the devil.
You both make good points. I think you are both making things a little more complicated than they need to be. About God establishing his authority I will just say this:
God is God. He did not rise to power. He created everything that exists apart from himself. If we can agree that originally he made things perfect in the heavens then we should have no reason to believe that God was not the rightful ruler. If we cannot agree based on those perameters then who ever has the right to rule or decide the way things should be? If you think under those circumstances that God does not know what is best and have the justified right to establish that fact then you are posing a challenge based on your own groundless authority. I am not accusing you of this but if this is your position you are being a hypocrite for accusing God of something you are doing. This is what the devil did. This challenges God's authority.
Now here is the problem. Given this circumstance how would it satisfy you that God was the correct authority? Would you endorse the devil's objections, and everyone else's? God would be agreeing with the devil that God does not know best and is not the correct authority. God knows this is not true and would be calling himself wrong and a liar. Therefore he must insist on his authority.
So that others know that what the devil is doing is wrong he calls the devil wrong. Would you at this point have God kill the devil? What about the next person like you that says God should not have killed the devil because it wasn't proven that the devil was wrong? Do you see the problem? The solution cannot be made to satisfy all possible objections yet.
So how would prove the devil wrong for his rebellion? Any ideas? God continued creating and created man. The devil seeing the opportunity for more rebellion poses the challenge to God that man should rule himself. What would you do at this point? Would you satisfy the objection and NOT act in a way that you can be accused as a tyrant? God allowed it that if man rebels against him then man can rule himself. You seem to think that God should simply intercede at every moment without ever letting the consequences of rebellion be known. The consequences of rebelling against God are chaos, pain, confusion, hate, pride....... God did not create these things. Those that rebelled created them. By simply allowing persons the freedom to rebel God proves himself right by the outcome of ungodly authorities.
You tell me how God can make creatures with truly freewill and prove his authority when they rebel in some other way that is more to your satisfaction.