Please DO NOT count on this happening.
Seriously.
The defender in this case fired "six or seven" shots, and achieved a forehead hit (certainly glancing, a solid forehead hit with a 9mm would decorate the opposite wall with brains) and leg hit. What happened to the other four or five shots?
They missed!
This is not a "minor caliber" (what a silly term!) problem, it's a poor marksmanship problem.
Come on. The only thing one can count on in these types of situations is the hope you're quicker than the bad guy, and hope the bad guy goes down first, without you getting killed in the process.
I was simply explaining to you the impact difference between 9mm and a .45. The difference is substantial and not even debatable.