> What prevents me from making Microsoft a 1% shareholder of my company Cockwombles Inc?

I don't see the mechanism by which this would be possible. Companies (and individuals) are not under some legal obligation to accept donations.

> Or giving them a specific exemption in my license for the cockwomble software library?

I've seen licenses over the years that say things like "this software cannot be used by companies or contractors working in the defense industry" or "this is free except when used by FrombleCo, which will need to pay me $500 per user." I suppose it's a way of expressing your disapproval of FrombleCo (or the defense industry), although I'm not sure how I really feel about that approach personally.