I mean I don't know. A joke which may have been intended to give a hint, while putting applicant at ease, has clearly backfired ; but if that's the worst interview they have had, they're pretty lucky.

I also notice the paragraph near the end with couple of general lines on good interview and the "that's how I hold interviews".

Here's the thing. Nobody sets off to intentionally be a bad interviewer or coder or manager or whatever. It helps to have humility and significant open introspection to be good at something (not the only path but for most of us it's the best path). We ascribe wilful incompetence to others while we have excuses and lessons learned for ourselves. Maybe - likely - the other interviewer too thought they were giving opportunities and signals and letting people at ease?