Generally I don't fully agree with the article, even though it has a point. But, they make the common mistake of mixing GNU and Linux:
"The worrying thing is, there is nothing inherently implausible about this claim. There are over 30 million lines of program source in a Linux distribution, if you include all the programming tools and utilities."
GNU is separate from the kernel. What is now commonly known as "Linux" is in fact GNU + Linux kernel.
More detailsIn fact, SCO themselves use and rely on several GNU tools, for example GCC and Samba. They use these tools even today.
This is why I consider SCO god damn hippocrats for attacking GPL and free software in general.