It was his right to do so and they shouldn't have had to shoot him, yet at the same time it is a bad idea for reasons that I have already outlined. It isn't wrong, it just isn't practical and might even be dangerous. It's displaying your weapon in a case where you probably won't be able to use it for various reasons.
Just like the old guy mentioned above who went out with his rifle to 'scare off' some people. Maybe in his time this was the right thing to do, but now more often criminals are wise to tricks and armed, and approaching them is a hazard. This poor guy would have hung himself out in any case for confronting without being able to back it up.
We don't have meddling hooligans who can be scared off by guns that you probably don't intend to use anymore. We have thugs who will kill you.