The software freedom law center makes it's living by taking companys to court over GPL violations. At best anything it says must be taken with a grain of salt. The fact is, no amount of gyration or hand waving can magically make Microsoft code belong to the community. Microsoft wrote those drivers from scratch, and therefore can license them however it wants. Period. They are not required to use the GPL unless they incorporate GPL code into the drivers, which they did not.
Some people like to say that if you link your code with GPL code than your code must be GPL. It doesn't even say this in the GPL though some say it is implied. It's an untested legal theory. It's never even been brought to court and it has a very good chance of loosing because the court is likely to take a very dim view of the idea that one person magically owns another persons work. In the normal case, however, it might fly... That is of using a GPL library in a non-GPL program or linking a non-GPL library into a GPL program. This might be seen by the judge as taking advantage of something not yours, but in the case of loading drivers into the Kernel where there is longstanding acceptance of proprietary drivers it would fail, and this precedent would put even the widely accepted case in jeopardy.
But more importantly, Linus Torvalds himself does not believe the act of simply loading a proprietary driver module in a running kernel is a GPL violation, and he has explicitly stated this in the past, which means a lawsuit over this "violation" would be impossible to win, and even impossible to bring, considering Linus would not sign off on it. In addition, this is hardly the first proprietary software driver for Linux. There have been many over the years. Many of the wifi cards that have vender supplied Linux drivers, for example, use proprietary drivers because of an FCC mandate that the wireless products are not end-user modifiable.
A lot of people like to believe copyright is cut and dry. It's not. Let me assure you that the copyright act, written for books, says nothing about weather linking against another work makes your work a derivative work, which makes it a judgement call, and this issue has never been brought before a judge. When it is, you better hope it's over a better case than this, because if it was brought under this case it would have a very, very, good chance of loosing.