Not exactly the most "fair and balanced" article.
Someone could write exactly the same article and claim Linux is ripping off Microsoft by using their past innovations. It would be equally one-sided and false. The reality is that there is probably truth on both sides of this dispute and that obscures the real issue.
The real issue is patents. We need to get away from this model of incentivizing innovation. Otherwise we will constantly have this conflict: someone will invent something (Microsoft), someone will want to clone it (Linux), and conflict will result.