Because a superpower does not start a nuclear war.
They simply cannot attack. The retaliation from OIN with IBM, Red Hat and others will be instantaneous. Microsoft would be attacking their own customers (every single enterprise today is using Linux and Microsoft together), which will fight them back. It is simply not going to happen.
What Microsoft is trying to achieve is to spread some more FUD (fear uncertainty doubt) about open source. They are hoping to slow us down. However, the more I look around, the more I am getting convinced it is actually already backfiring.
What Microsoft is showing the world is why open source is much better. No open source project will attack you. Not only the software is better, with a community supporting you, where you control your destiny thanks to the source code (and no lock in). But you also have assurance nobody is going to sue you because you want to use a competitor... Better and cheaper software, with no objective risk associated.
What Microsoft is giving us is really 235 more reasons to love open source. I made a t-shirt of it.
Monday, at the Microsoft Open Source event in San Francisco (a PR attempt from MSFT to show the open source community still loves them) I am going to wear it. Actually, I am going to bring some with me, in case you want to also show Microsoft why we are thankful of their latest move. I'll bring some at OSBC as well on Tuesday, just in case nobody shows up at the Microsoft event :-)