That's one of the things I wanted to come to a consensus on.
We have to use the same definition of reasonableness.
I think a reasonable person should be able to , with a fairly high degree of accuracy, tell if a person is approaching them in a menacing vs a friendly way.
The reason I started this thread was in part to illustrate that surveys that attempt to quantify the number of DGUs don't really define the term.
The DoJ reported that about 1% of reported crimes involve a victims use of a gun in self defense. In that same report they also acknowledges that only about half of all crimes are reported.
https://bjs.ojp.gov/content/pub/pdf/fv9311.pdf
The number of DGUs was significantly higher than the number of murders and even though I really don't think the number of DGUs matters that fact alone should be enough for anyone to support the 2nd Amendment.