We have no idea why Max Howell was rejected. Only the interviewing team knows that. Maybe there were a variety of other problems. Maybe he came off as a complete asshole during interviews. Often not knowing something is fine during an interview, sometimes the point of the interview is to see if you can ask good questions and collaborate with the interviewers, take advice, without becoming defensive or combative.

Even if feedback was given after his interview, it's often the case that the real reasons are too sensitive or controversial to feed back.

You can't trust a candidate when they complain about why they were rejected. They really don't know.