Everyone shut up and get to work. Problem solved.
These are thoughtful, intelligent, well-educated knowledge workers. There is always going to be dialogue between them, the sharing of ideas both progressive and regressive.
Google is trying to manage that dialogue by providing a platform. Otherwise it just becomes something embedded within the company culture. The sort of thing that employees talk openly about until someone from HR enters the room.
Diversity hiring practices are a discussion matter for HR and hiring management, and discrimination or harassment is a discussion to be held with HR. If a company provides a platform and invites employee dialog about HR matters, then they deserve whatever they get. Firing people after inviting their opinion only creates unwritten rules about who is really allowed to contribute to the dialog. Employees only need to know the rules and the rules need to be clear. It doesn't matter what I think about co-worker's ethnicity, gender, sexual orientation, or how that impacts them having a job, unless I say something about it. If I shut up and do my job, then my opinions don't affect me or anyone else.
Why would a company create a platform for discussing diversity issues, and then allow that platform to be used to promote views that are against company policy.
Providing a platform is a way for the company to have some degree of control over how these issues are discussed, and to intervene where employees are expressing attitudes that are damaging to company culture.
I know that in a place like intensitysquared where everybody loves unadulterated freedom of expression, that might sound like a nightmare. But it actually makes a lot of sense for a company to do that. Particularly when that company has a huge public profile and an image to maintain.
(I may be playing devil's advocate here - or maybe not).