As funny as it is, I think there is something deeply wrong with a person who thinks flashing his naked body is the best first line response to an annoying person knocking on his door. And people doing that to children is, at best, super disturbing.
The householder has many other options, including not even answering the door, or opening it and yelling at them. Of all the options...why does he reckon NO PANTS is the best one?