That doesn't change anything. The metric is useless in the context presented by Microsoft. It was picked because MS ranked on top on this one. That's what I already implied in the original post.

How you structure your team(s) on GitHub has nothing to do with your "commitment to opensource" or whatever your marketing phrase is.

Microsoft has several other github organisations, so they weren't representing the total "company" contributors for themselves either.

e.g.: They have separate github organisations for: https://github.com/Azure https://github.com/PowerShell https://github.com/aspnet https://github.com/dotnet

(and many more smaller orgs as well, as I'm sure google do too)