That's an interesting view of what a monopoly is. By the same standard, Google can make their own OS (actually, they do), so it should be right for Microsoft to prevent Chrome from installing on a Windows box, right?
I was about to say the same thing...
Imagine one day if Microsoft modified the e-cert store in Windows to prevent any e-cert with the name "Google" in it from being added as "trusted", so all current Google web applications will look broken in some way. Will Google cry foul?
Edit: Okay, this is not good example, but maybe if Microsoft modified Windows certificate store to only trust a special subset of CA, and make secret deal that those CA will not produce e-cert for Google? This is actually feasible because most CA in current database has expiration date from 2015 to 2025. If Microsoft would willfully neglect to put their new cert in the updates for the database, these CAs will no longer be trusted after the original CA e-cert has expired. And given the number of Windows machine, we could effective call Microsoft has the access to kick them out of business.