I'm extremely confused. I hope this is sarcasm. What are you suggesting is the proper course of action when 3 armed people break into your house? Are you saying it is cowardly because the hero had a better weapon than the violent intruders? That's kind of the point. You should never be forced to participate in a fair fight in your own home. The more unfairly the fight is stacked in favor of the innocent person in their own home, the better.
Let's imagine what it would be like for you if you were in this situation. You are asleep and awoken by the violent noise of someone breaking into your front door. You rush out of your bedroom to enjoy beverages and fellowship with these people. They stab you in your face. You die. Your last thought before losing consciousness is the smug condescension that at least you didn't shoot these guys because that's what a coward would do. Then they kill your dad. And steal your shit. The end. Your way sucks.
Good question, I tell you what I would do, I would try to avoid situation like this by making my home more secure, following these measures:
If you are more wealthy sooner or later someone will want to rob your house so first you:
1. Build a fence around your property, including sliding gate to driveway.
2. Have installed reinforced doors and windows. - Reinforced door with steel frame and no glass in center, it's not penetrable unless using some pretty big axes or lock being destroyed by guns. Reinforced window is still penetrable if glass is broken but cannot be opened from other side by any other subtle means(like pulling, or releasing lever on window slightly opened).
3. Do not leave gate or doors opened/unlocked! Even when you are nearby.
4. Do not leave opened windows on part of house you are not nearby if it is big enough and you would not be able to attend what is going on there.
5. Have motion sensors, cameras might be good option too. Leave alarm armed at parts of property you don't visit much often.
6. Get a dog.
7. Don't leave curtains open all the time on your ground floor, everyone will see your stuff.
8. Do not store money, gold, jewelry and other expensive stuff in your home, period.
9. Then if you have all of that, get guns.
90% of thieves won't come near your house and those few who do will not get in without alerting you way before any physical encounter will take place. Which gives you extra time to call the police or take cover.
Seen in the photos from the scene the guy likely had no security at all, and guys got inside with zero effort, but hey, he did have guns after all.
If you want to actually prevent something you do take measures that will reduce chance of that happening greatly. Once someone is inside it's too late, that's when guns kick in. But guy did just that, he had guns bud did practically nothing else to prevent that situation.
Did you even know that if you have your house insured, and it gets robbed, you will not be able to claim damages if you had door unlocked or windows opened?
Now to your question:
I would order them to leave, if not complying, few warning shots would be shot near them. By that time they would be very unlikely still there or trying to subdue me, but if yes they would be shot to places which would not kill them but would render them incapable of harming me. In any case I would definitely not shoot on sight unless the guy would also have a gun and would start aiming at me.