There are flaws in your reasoning. Patches / employees will not deliver more flattering numbers for Canonical, it will generate an error. Since neither Debian nor Gentoo has any employees at all (and that's why Debian isn't mentioned), their contribution in this respect is infinitely higher than that of Canonical. In the same way, counting spare time developers from Gentoo and Debian on par with salaried developers of Red Hat or Novell is irrelevant.
Perhaps comparing users / patches is a better statistic? Well, different distros attract different types of users. I'd guess that the communities of Debian and Gentoo are more technically inclined than the community of Ubuntu. Besides, Ubuntu has a pretty large user base - so that'd be neither better nor more flattering for Ubunto, I think.
So, what is there to compare? I suppose what's left is patches from companies generating revenue selling Linux. And if purely community driven distros show up on the charts, let them stay as a reminder to those who actually pay salaries to developers. Wind River, rPath and Mandriva may find themselves similarly challenged.
This does not imply that I agree with Greg. I think it was shortsighted to not include Gnome/KDE/XFCE in the comparison - not that I know if it would have made a difference.
It does imply that I think ubuntuers are whining, however. A more suitable reaction would have been: "Shit! Are we at the bottom? Well, we'll overtake rPath before the next time he gives a talk. And, Mandriva's next after that!"