They are phonies. They did look ridiculous.

And yet, they knew the police would not come. They knew these folks liked to burn down buildings. And, they knew if they waited until their house was being attacked, it may be too late with no police or fire on the way. This is when reliable police response prevents conflict, because people don't have to take matters into their own hands. I would argue that they had a lower threshold to do what they did given the likelihood the police would not come.

I could see standing there with an AR, and aiming only at people who stepped on my property. But, it depends what state you are in. In the Northeast, that would probably not fly...the courts would probably say the homeowner had a duty to flee. In the South, most jurors would say that you shouldn't step on someone's property if they are displaying a gun and you don't want to get shot--it's just common sense.