I don't think it's reasonable to expect your co-workers to openly protest any issue. People have families to take care of, paychecks to earn and rent to pay. They for the most part, want to do their job with minimum of drama. I'm sure there are a million issues that the memo author was not openly protesting that other co-workers may have cared deeply about. I would hope they wouldn't hold that against the author.
I'm not questioning whether this person experienced racism at Google, as that seems likely in an organization of that size. I just don't think it's ok to be upset about your co-workers not being openly vocal in the workplace about a political issue you feel strongly about.
There seems to be a strong push to politicize silence that seems very unhealthy. You don't know how people feel and act outside of work and the public sphere. Silence on an issue is not a political statement.