Did you even read the article you linked to? I quote (from your linked article):
Now, some of Spider's code (possibly all of it) was based on the TCP/IP stack in the BSD flavors of Unix. These are open source, but distributed under the BSD license, not the GPL that Linux is released under. Whereas the GPL states that any software derived from GPL'ed software must also be released under the GPL, the BSD license basically says, "here's the source, you can do whatever you want, just give credit to the original author."
However, it looks like some of those Unix utilities were never rewritten. If you look at the executables, you can still see the copyright notice from the regents of the University of California
And the software was licensed perfectly legally, since the inclusion of the copyright notice satisfied the BSD license.
Why would they include the original copyright if they weren't using the code?
It's true that MS's use of BSD code was perfectly legal, and it's completely unfair to say MS "stole" it. However, the point remains. MS still uses code from BSD (which has ALWAYS been Open Source, just not GPL - the BSD license is an Open Source license) for it's Unix services, FTP, and a few other purposes. Nothing wrong with that, but that's not the point.