I think that citing this example every time "hiring at Google/Big tech" is discussed on HN is useless.
We know that there are a lot of false negative and and lot of chance in the hiring process (so many things can fail in a process involving so many steps and people).
There are also legitimate rejections, like hm, bold statements ("90% of your engineers use my software"), fingerpointing or not being able to seek for assistance when you don't know something.
I discussed interviews with many people, and I'm convinced that solving the problem with the theoretically-optimal solution is not the only way to get a positive review. Being open about things I didn't know helped me: for instance "Hm, I'm not sure about how to do this exact thing, I'll use the function do_this_thing() and implement it later if I still have time, if that's OK for you" buys you time and allows to keep the discussion focused on the main problem.