21' "rule"?
And many MANY years ago I got sucker-punchrd outside a bar in exactly the same scenario. Guy got tossed out, I left about a minute later, knew nothing about his issue, he asked me for a light, when I reached into my pocket he whacked me with a bottle on the side of the head. If it wasn't for witnesses and a cop cruising by he never would have gotten caught. I ended up in the hospital with stitches.
I don't know the whole story, but it's certainly plausible. Her hands would be occupied opening a purse and she could get mugged/assaulted fairly easily. No mention of what the guy looked like, how he was acting, etc. I'll wait for more information than was in the article.