Kudos to the guy for admitting he was wrong, but I wouldn't celebrate it too much.
If they're able to disregard and misinterpret all the available proof regarding Earth's shape, something is fundamentally wrong. Either they lack the... mental acuity to deal with abstract concepts, or they're severely lacking in critical thinking.
At least the second one can be overcome if one commits to learning in a structured way, but the first one...
Hey fellow programmer! This is definitely a thing for me too, it's uncanny how frequently some random tidbit about a piece of architecture that I've tinkered with as a hobby years ago becomes relevant, and I just blurt out to a colleague "oh, do this and that, and it should work".
But on the other hand I have to pause for like 30 seconds up to a full minute before answering when is my kid's birthday, just to make sure I'm not getting it wrong somehow. π