I've personally never been comfortable with carrying behind me (SOB or 5 o'clock). I don't like the thought of my firearm behind me for many reasons. Just my personal preference. At the most, I sometimes carry at 3 o'clock and mostly at 2. I would prefer 11 o'clock for a crossdraw with my right hand, but it is impossible to sit down without having to adjust. 2 o'clock seems to work for me.
I was just thinking as I read the story if the guy had his IWB towards his front he could have drawn his weapon as he was walking with his back towads the BG. Another option given his circumstance was a weak hand shot when the BG was at his 5 position (under his right arm/elbow). You can't prepare for every possible scenario. Glad he's alive to tell the story. Scary stuff.