I know that—I have pepper spray for self defense for that very reason, along with other weapons.

The issue is that you have to feel reasonably threatened still. For a gun, the bar is serious harm, and for pepper spray it can be a much milder threat such as approaching or violent words.

I just don’t see how “hello” is threatening before a verbal order to leave the property. That’s why I think the video is important—her attitude and stance will make a huge difference in how justified the response was.