If it's self reported (which seems to be the case from the article, I could imagine that people reporting under 11 hours might be using different criteria for what they really consider sedentary activity compared to those that report over 23 hours a week. I fall closer to the 11 hours a week (standing desk, bike to work, bar height dining table at home) but agree that even with all of that it'd be rare that I'd be sitting for less than 1.5 hours a day (especially factoring in weekends).
