I think people were making fun of Google, because it is a caricature of their whole interview process.
If a large number of your engineers is using Homebrew, having its developer is an asset for many different reasons (e.g. influencing the focus of the project, getting formulae in that interest you, or simply improving a tool that is important to your productivity). But no, they reject him because he cannot invert a binary tree.
It's like throwing one of the better offenders out of your soccer team, because he cannot substitute as a goalkeeper.