Something is definitely sketchy here. From what I've read, it was a S&W M&P 40 carried in a soft holster in his waistband. I haven't seen the mention of a shoulder holster mentioned; although, that would make the most sense. First it was a hug, then it was a hug from behind, last I saw it was dancing. Of course, we're depending on the never let accuaracy get in the way of getting the story out first media to inform us.
I generally don't now that I have settled on a carry system that I like, but I have carried using some fairly inexpensive and soft holsters. I still don't know how you would pull a trigger through pants and holster.
As far as the impact location, I would think it would be plausible (still unlikely in my opinion) that an approximately 5 ft woman "dancing" low behind a 6+ ft (speculating as I haven't heard heights or done math) man could end up in the exact position needed for this to happen.
We have to remember that he's innocent of wrongdoing until proven otherwise. One in a million events do happen.