OK, well to hijack an old saying...
"If all you have is a gun, everything looks like a target"
In his case he also has a phone and a good vantage point. I'd assume, also, a locked door. It's also a good tactic (that can very much work in your favor) to have first called the police in case things deteriorate to a deadly force situation.
Consider a jury made up of retired folks who don't own guns, and aren't your peers. An effort to call the police before hand rather than handle it yourself would go along ways toward preventing you from going before the jury in the first place.
We shouldn't get ahead of ourselves. Singing and banging on a sign aren't at the highest level of seriousness. Nor should it be ignored.