Their own code?
Seems like nobody (including the author) did bother checking what happened. I have tried, taking into account the very few facts that this article references.
MS (in this case, I'm not speaking about th rest of what they did) did not "steal" GPL code. As the article pointed to by the author says: "Microsoft originally was licensing the Linux drivers, also known as the Linux Integration Components (LIC), in a way that was in violation of the GPL. It was offering them under a combination of the GPL and a closed source license.".
In summary (unless somebody can bring more facts to the case to prove I'm wrong), what they did was:
- write some product (Hyper-V) and a bunch of Linux drivers to make the OS work with the hypervisor
- license parts of the drivers code (which they did write) under GPL, so that these parts can be integrated in the Linux kernel
- people complain that this newly GPL-ed code now is beeing linked with non-GPL code
So yes, technically they did infringe the license, but with their own code. Not like if they had taken parts of existing Linux code to put in their closed software(OK perhaps they have done it, but this story does not show it).
If id had been possible to write linux drivers which are not GPL code, probably MS would not have GPL-ed anything at all. They thought they could go away with releasing "stub" code which works with their closed code. Like others do (hint: look how some gfx card drivers are implemented).