This happened the other day. Self defense question out of Detroit?

All parties involved are between 30 and 40 Y/o. My cousin got involved in a neighbor dispute. The neighbor (#1) to his right had gotten into a nose to nose confrontation with his neighbor (#2) to the left about neighbor #1's kid running over #2's garden repeatedly. After #2 said "you need to keep an eye on your damn kid" Neighbor #1 threatened to kill #2 and said out loud that "he was going to get his gun" and "This ain't 1963, we be killin' pink M*ther F*ckers's like you now" and continued shouting racial slurs and violent threats as he turned and began to go back to his house. My cousin, who had his 5 yo and 1yo in the front yard as this was happening, stopped the guy and told him to calm down because the kids didn't need to hear that kind of Sh*t as i collected the kids into the house and loaded my cousins' 12 gauge which remained with me, in the house, after I called the police. At this point the guy started in on my cousin with the same threats "I'm not afraid to go back to prison! I'm gonna kill all you pink rabbit mother f*ckers!!" at which point he returned to his house. The area is a high crime area and I'm thankful it only took the cops about 3 minutes to get there and they caught the guy before he came back out with his gun. My question is how much force would have been reasonable to prevent that guy from even getting to his house to retrieve his gun in the first place, since his intention was absolutely clear? This is a serious question. I'm a hunter and practiced marksmen, I was locked and loaded, I checked my field of fire and I was ready to remove his head if he had produced a firearm.