You can get a know it all from any profession. Professors do seem prone to it, but not all of them. I've met and worked with many professors in many capacities and found good and bad. We've argued and agreed on a huge range of topics.
When I was twelve, doing odd jobs around the neighborhood to earn spending money, I worked for the couple across the street that were both professors. I quoted them a price for doing three different things, raking leaves for $35.00, mowing the lawn for $15.00, and sweeping the driveway for$10.00. I got done and went to the door to collect payment and she handed me a $50. I politely said the total was $60.00 and asked for the remaining $10.00. She said "But the total for what you quoted me is $50.00" Then she named each item and what I quoted her, and did it correctly. I agreed with each amount as she named it and when she finished she was looking at me triumphantly.
Now, I knew she was a math professor, but I knew I was right and I was determined to get paid for the work I did. Not knowing what else to do I got my note book out of my pocket, flipped to the page where I wrote down the work she wanted and what I quoted. I showed it to her and she agreed what I wrote was correct. Then I started adding it up on paper in some blank space at the bottom of the sheet. I felt like a total fool showing a math professor how to add on paper. But when I was done she turned bright red, ahhhed and ummmed a little and then, with an air of superiority, said "I was testing you, good catch, you passed." No sorry for being wrong, no oops don't know how I did that, just pretended like she was somehow right the whole time. She opened her wallet, got another $10.00 to add to the $50.00 and I thanked her and left.
My next experience was working for the Dean of a college. He was the nicest, down to earth, humble and hard working sort of guy. You would never have guessed that this guy had been the Dean of a huge old college. This man had literally dined with statesman and kings and dictators, traveled the world many times over, spoke several languages, held a few patents, and the list goes on. When I worked for him he was in his nineties, seventy years hence a farm boy, his favorite activity was working in his garden. Even at his age he was sharp witted and able to work hard all day. The funny thing was he ranted about the direction colleges were headed, and this was almost twenty years ago. He didn't like the character he was seeing in students and staff. He has long since passed on, but stands out in my memory as the kind of person that colleges should turn out and promote. He had forgotten more than most of us will ever learn, but it was like he didn't realize it. He was curious like a little kid, was eager to listen to anyone on any topic, worried if the frost would kill his tomatoes and framed crayon pictures from his great-grandkids to hang on his study wall.
When I was reading about the professor in the OP I was thinking about the math professor. Smart person that somehow thought it made them better than average, having a hard time admitting they might be wrong. As the argument about professors unfolded I remembered the Dean and wondered what he would think of the whole thread. Like I said, you get good and bad; it is up to each of us to choose which to be. We'll project who we are no matter how we try to appear otherwise.
Mr. HE