I remember the controversy when this happened and some follow up within the next year or so. After that I never heard any more about it and always wondered how it ended up. Glad to know.
As far as the the appropriateness of the Ranger home-owner's actions this situation is obviously is NOT the typical self defense situation. Having a group of drug dealers pubically tell you they are going to shoot you, and then actually following up on it, is so beyond the typical situation that it has to be looked at as it's own unique situation.
The Rangers did not fire until they were fired upon. They wanted to keep the attackers from getting close enough to either storm the house or be close enough to take better aim. I'm sure they also wanted to reduce the amount of incoming fire by returning fire at the places where the shooting was coming from. Yeah, you could call it "suppressive fire" in that they were probably firing at muzzle flashes, but it seems that was what was needed in this case.
It sounds like most of the "innocent bystander" neighbors were already at the Ranger's house, which helped reduce the potentional for injuries or fatalities to bystanders.
Still, the men in the house were still responsible for every shot they fired. If they hit an uninvolved neighbor or an attacker they would have had to face the legal criminal and civil consequences. That was a risk they took even if it turns out to have worked out.
This is a neighborhood, not a battlefield. Firing at muzzle flashes doesn't seem to fit this definition.
If multiple attackers are shooting at an occupied house and the only thing the defenders can do to stop the attackers is to return fire *and* the only target they can see in the dark is the muzzle flash, then shooting at the muzzle flash seems like a reasonable thing to do to stop the attack. You'll either hit the person shooting at the house, which stops their firing, or you may cause them to duck or run off, which stops their firing. Either way the number of incoming rounds is reduced and the chances of someone in the house being hit is reduced.
Granted, as I said before, the defenders are still legally responsible for their actions and all the shots they fired. But, I think firing at the muzzle flashes would be appropriate in those circumstances. If the defenders would have waited for a clearer target before shooting the volume of incoming fire would NOT have been reduced and there would have been a greater chance of injury to those in the house and if there was no return fire the attackers might have attempted to rush the house. As it stands it sounds like when one of the attackers did attempt to close in to the house, and was identifiable as a specific target, he was shot.