note that the earlier comparison you point at is comparing the size of compressed source archives, while this one is comparing lines of source code. remember things like logos will not compress well (and will not count as many lines of code either)
they kernel hasn't quite doubled in that timeframe
2.6.21 is 10332702 lines
3.0-rc1 is 16700965 lines
but it's gown a lot. have the GNU tools been growing that fast?
in any case, unless someone points out a flaw in the tools (as opposed to just other studies that did other types of checks) I don't have reason to believe that the numbers presented in this article are wrong. the code to run this is available, so if you think there's a mistake in it, point it out.
given how large gcc and gdb are, I would be interested in seeing the results when run against the standard install rather than the entire repository