FWIW, I was trying to posit a situation in which you don't have time to respond. I was using flat earth as a stand-in for a wrong statement, and oftentimes, it takes more than name-dropping Galileo to demonstrate that the writer is factually incorrect. I agree that if you have time, demonstrating the truth is the best option.
You should do what feels right to you.
What would I do? Probably click reply and challenge my fellow hackers with something like, "Who you gonna listen to, Galileo or Thomas Friedman?"