It's a symptom of the internet, we don't talk to each other like people and when confronted even in the gentlest of ways with an opposing viewpoint or correction to a false claim it goes directly to insults and doubling down on the original claim almost 100% of the time. Where is the shame in saying"okay, I didn't know that, my bad"?

I bet he deletes the comments eventually, seems like they at least realize they are wrong now.