"Welcome to the free market, where private companies are free to hire or not hire at will based on criteria that works for them. Writing OSS doesn’t entitle you to any job."

Nobody is saying anything other than that. They're pointing out how dumb the decision is.

"Also “inverting” a binary tree is a trivial computation exercise."

It really isn't, especially if you're not doing it on a regular basis. Which I'd contend 99% of people, including those at Google, are not doing.

"There’s a difference between engineering and scripting. Homebrew is very much a scripting problem."

Aside from, you know, the entire infrastructure around it. That is very much an engineering problem.