Some insight into why they may have hidden the down arrow ratings.
http://www.redstate.com/2012/09/01/our-failing-disqus-experiment/
No, that article you linked is 18 months old. NRO has always had different customization than what is described in that article.
NRO made the change on a Friday mid-morning. Why not at the end of a day or over a weekend or at the start of a month? In fact, NRO went back and edited the negative ratings of all previous posts for all stories from all previous dates.