Humorous answer: Maybe I can't invert a tree, but watch me flip this table. Serious answer: Companies that pull this crap deserve to starve and die.
What specifically are you objecting to? That specific question? Writing code on a whiteboard? How would you interview software engineering candidates?
If you're not at Google's scale, a take-home test that involves them producing a working solution to a problem in their own time, that you then expect them to be able to discuss, reason about, justify, and so on is a much better tool; even at Google's scale, where you might be worried people who copy answers off the net, have them bring the laptop they used in, and then get them to expand upon their solution.
All that said, I'd be surprised if that was the only factor at play. The Twitter comment itself seems to indicate a - uh - cultural fit issue. Additionally, and with no actual knowledge of the insides of HomeBrew, that a piece of software is widely used isn't evidence that the author is an excellent (or even good) developer.