It's a sad situation... from what I remembered, there were a lot of push in robberies. Not sure of his area though. And secondly, home protection is always key, you never want to give them the opportunity of gaining a foothold in your home. The door is the easiest point of attack because it's a narrow access point.
But it should be done legally.... following the guidelines set in that state...
Though it begs a few questions.
It's normal these days to have a cellphone instead of a home phone... but how many times have you fallen asleep in your bed without your phone close at hand to call the police?
You seen a shadowy figure in the peephole move towards the back and knock there... After ensuring the target is empty, crooks don't knock for long.
There is a step process from getting your weapon and loading it for use of home protection in Michigan... which took longer than fishing phone out of his jeans pocket in the bathroom.