If you focused on what Greg was saying, and didn't get emotional about the way he said it, his points were correct and for the most part Canonical (via Mark Shuttleworth) agrees. For the community of developers who do "Linux Plumbing", the feedback loop from Ubuntu is currently disconnected. From Greg's position and point of view, this in inarguably a Bad Thing.
Speaking for myself, I'm a bit more ambivalent. The developer community Ubuntu must keep happy over all others is the Debian developer community, just as Red Hat and Novell must keep the ecosystems around Fedora and OpenSUSE alive and vibrant. If Red Hat Enterprise Linux and Suse Linux Enterprise Server feed off of their open communities, one could argue that Ubuntu has a stronger base from which to start and, given their desktop focus, not as far to go when building their distribution.
We should also keep in mind that Canonical gets press in far greater proportion to the size of their company. I would guesstimate that Red Hat has between one or two orders of magnitude more engineers on salary than Canonical.