Mono has IP?
Yes it has. Just because a project is open-source that doesn't mean it isn't protected by IP laws.In Mono's case only Novell/Attachmate were able to dual license the runtime libraries, otherwise licensed under LGPL, making it unsuitable for the demands of companies wanting to embed Mono in games (just an example).
Also, MonoTouch and MonoDroid are commercial products and Xamarin had no right to distribute or use in any way any source code or binaries from those projects; meaning they had to start from scratch in producing alternatives which would have been in a gray area, not to mention waisted effort.