Incorrect. I know several people working on Google projects as temps (with Google-provided laptops and @google.com domains) and with the code and technologies they're working with there is no way they can work without Homebrew. Maybe it's different for full-time employees but I doubt it.
Not OP, but Googler here. We use an internal Linux distro for all our development. It's very similar to Ubuntu (so the default package manager is apt). People who have a Macbook use it as a thin client to ssh into their Linux desktops. So OS X package manager isn't really needed or used.