Now, considering that Linux didn't even double in size over the past 4 years, which would still put it ways behind the size of GNU back then, and that GNU also grew in this time-frame, I wonder how the report could possibly have arrived at a similar proportion of Linux and GNU.
But then, code size is not the whole story. Linus himself wrote, in the Linux 0.01 release announcement, that a kernel by itself gets you nowhere, and most of the tools used with linux are GNU software. So even he thought of linux as the kernel alone, and that GNU was essential to get a complete functional system. http://www.kernel.org/pub/linux/kernel/Historic/old-versi...
This relationship could have changed like his opinion did, but it didn't: the combination of these two powerful developments fed each other and grew together and mostly inseparably, so neither party can reasonably claim credit alone.
That's why calling it GNU+Linux is just reasonable and fair. Calling it all Linux just feeds the misinformation for people who misperceive Linux as more than what it is. Of course those who seek this undeserved credit and want to spread misinformation will fight for it, finding other excuses to explain why it is fair to promote a small component of the whole over another equal-sized if not much bigger, older and just as historically-relevant component.