Does he write a column every week, on a regular day, or just when the spirit moves him? The syndicates require regular copy on a specific schedule. I think he would have had syndication offers by now, probably from a syndicate like Creators, which syndicates Michelle Malkin. Perhaps he didn’t want to to be tied to a weekly deadline.
That could be it too. Maybe a regular reader would know.
Looks pretty regular.
http://www.wacotrib.com/opin/content/news/opinion/nugent.html
Those are his column archives there