1. The act of trespassing does not make all rights null and void.
2. You cannot use deadly force against someone who is merely trespassing as you have no reasonable fear of death or seriously bodily injury.
3. The instruction that the judge would read to the jury before a self-defense case is decided is that the defendant must be in a place where they have the right to be. Boyd was not in a place where he had a right to be thus his right to self-defense is null and void.
Bingo.
Well if I and 5 of my buddies have rifles pointed at a guy with a pocket knife 15-20 feet away (not to mention a trained K9), I can't honestly say I would be in fear for my life either. This didn't go down in a dark alley, in a one-on-one situation. They clearly had the drop on him. Right or wrong, that's what a jury is going to see.