Exactly. We don't know anything the author didn't tell us. For all we know, the author adamantly gave the wrong time complexity for quicksort. Or also possibly they were (intentionally or unintentionally) rude and condescending. Or there was a way candidate with a way better fit than our plucky author. Or, or, or....

Thankfully the author left the name of the company off. I'd hate for half of a secondhand account like this to cause candidates to avoid interviewing at a company!