Hey Physics,
CBS has changed around their site a bit and they may have taken down that sentence.
I can only say that it was written in the old version of the web page.
From what I understand CBS starts looking over regular decision application only after they have checked all early decision applications.
So I guess it doesn't really matter on what date they actually start to check the regular decision apps. It will be later on in the process.
I am sure you can send admissions a email regarding specifics or ask Matthew on the ask Columbia GSB Admissions feed.
ask-columbia-gsb-admissions-121805-260.html