This simply demonstrates that a person can be ambushed.
There isn’t a cop in this country that couldn’t be knocked out from behind while in uniform and armed.
Guns aren’t magical. I don’t think open carry would have mattered a wit in this case.
I think the rapist would never have attacked her if she was openly armed. Most rapists say they do not attack armed women.
Most robbers do not attack armed cops either.
Predator learn to go after easy prey. If they go after dangerous prey, they may win a few times, but the odds are against them.