A very underestimated shot. I love the child's arms up in the air in the bg and you leaving all work-related paraphernalia on the table...cellphone, car keys etc. well done!
First, I think your score was hurt by people that didn't think this was a still life. Now, on to the photo. A couple things jump out at me at first that I don't like. The background could be improved by removing the couch, I think a full white background would improve the image. The out of focus elements (primarily the child) would have been a bit better had they been a little more in focus. A bit more nit picky, I think the pile of stuff is a bit too much, it seems more like clutter to me. I probably would have gone with keys, phone and watch. Would any of this improved your score- I have no idea.
In a challenge with a different, more fitting, topic, this probably would have done much better. The DPC crowd is kind of a stickler for meeting the topic. Still lifes tend not to include people and/or animals, so some people would vote you lower on that alone. Additionally, on some monitors, your image may be seen to have blown highlights. I like the way the image looks and probably would have given it a 6.