That shit don't fly. I would have confronted him right then and there and point blank, put him on the spot and asked him "why he chooses to treat __her name __ with seemingly dismissive disrespect, even while in front of me, but I'm perfectly fine to talk too?"
There was a time in my life when I would have done that. However, the longer that I live, the more that I realize that neighbors like this are snakes.
They are spineless like snakes. They move around in places that you don't notice them like snakes. They are able to blend in with the terrain like snakes. They are opportunistic predators like snakes. Lastly, like the talking snake in a garden long ago, they lie with impunity.
He may look like a harmless character but trust me, I've seen too many back-stabbing, lying, cheating turd balls like this. It's characters like this that I don't get aggressive with or debate anything with.
In desperate times, it is a neighbor like this that will make a phone call to the gestapo or the stasi about you. If they disagree with you on guns or anything else, they will take it personal. Then when the opportunity presents itself, they will get even with you for hurting their feelings.
I've got to the point that I treat these people like they would do me. I'm not going to try to convert him. I'll smile and wave like a Madagascar Penguin. I'll talk with them about how great their lawn and flowers look. I'll complement them on their handy work on their house or how nice their gazebo looks. If they ask me about my guns, I talk about air guns which seem harmless to the uneducated. Otherwise, I don't know anything.
If you were ever in the military remember some of your training and turn the map of the battlefield around. Become your enemy and think about their mindset. Think about every dirty trick that they will pull to save their skin or shit on you for having an opinion that causes snowflakes to melt.
Learn to think like them and don't ever get confrontational to their face. Most of us are reasonable people but when you look at people that don't behave in a rational or decent manner then they are not reasonable to begin with. That means they will act like Wally Cox catching butterflies but will eat you alive with deceit and treachery every time.
More and more, this country resembles the former Soviet Union, Red China and Nazi Germany. Those countries had plenty of snakes like this neighbor.
Rant over.