Actually, I think the other key argument is here:
> I believe that every successful language must have a
coherent vision that is shared by a relatively small group of people.
He points out that there are over 100 committers, nearly half of which are non-Google; it's only the small group of people in charge of the language spec that are at Google.
It may be true that Google the company don't drive Go the language. However, simply working in the same company tends to make you take on the perspective and values of that company.
In the Xen Project, for instance, Citrix is the largest single contributor. Citrix management have basically left the engineers working in the Xen to our own devices; but nonetheless we've made a conscious effort to diversify the organizational membership of the core decision-makers in the project: partly to make sure that we're not drifting into a Citrix-centric groupthink, and partly to avoid the appearance of Xen being a Citrix-only project.
If I were them, I would be looking for an opportunity to arrange to have at least one non-Googler on the core Go team, for the same reasons.