alt Hacker NewsFrom the details I read in the post you are almost certainly wrong, not to mention being reallying condescending.
The interviewer has control over the room. They steer the conversation. They could have stopped this at any point. Instead they encouraged OP to go deeper for 90 minutes.
That wasn't OP misunderstanding a question, that was an interviewer enjoying the power trip.
Should OP take their mom next time to shut things down for them? You don't have to do what others ask of you, you know. I stand by my original assumption - they were too inexperienced with the world to know you can tell someone no, or lacked the ability to do so.