What I don't get is that the T2i and 60D are selling better than the D7000,
Where did you see this?
As well, there seems to be some confusion about exactly which year is being referred to in the article. The D7000, D60 etc. are relatively new and may not be driving the reported stats. It would be far better if these data were broken down by camera model for each line. The Rebels may form the lion's share of Canon sales and possibly lead.
The difference between N and C is greater than the S share, which is a bit staggering. Suggests that C is doing a much better job at marketing. This also includes a better nomenclature system (even if the Rebel name is a bit stupid, IMHO, if not "loaded") for the amateur grade models. Also, as Thom Hogan points out on his web site, N seems to have a chronic supply problem. Is the N and C sales difference a consequence of this problem?