That's true for most crime. Its unlikely any predator is going to attack a prey it perceives to be as strong or stronger than itself. I don't see how this is some kind of revelation.
In 100% of "KO" attacks, weakness is a factor.
In less than 100% of "KO" attacks, race is a factor.
Therefore, we should be more concerned about people appearing weak, particularly since we cannot change skin color.
Get grandma some handgun training and a carry permit. Buy your great-uncles some NRA gear and matching fanny packs. Help grandpa dig out his Vietnam camo, and a 1911 too.
We can't change how we look (skin color), which is part of the targeting system for many, so bitching and whining about it on message boards is just plain stupid. It's what weak people do - bitch and moan about the attackers. HOWEVER, we can arm those around us to be ready -vigilant with eyes on the bad guys. Toss in the training to cap attackers, along with some dressing as a deterrent, and voila, we are capable about doing something about this "KO" game.
I mean, aside from bitching about it on message boards. That's fun too!