If your goal might be to nudge your colleague toward improved critical-thinking skills, this doesn't seem like a good tactic.

Actually, I tried to explain to him why we no longer fly to the Moon - for the same reason we don't fly at supersonic speed, the same reason we don't travel to Challenger Deep. I explained to him that the lunar rocks are absolutely unique and they can't be faked. I told him about zap holes, about people watching TLI burns. I told him that many people watched the launches and the craft went to somewhere and it was not LEO, because a lot of people would have seen it.

He refused to listen and continued claiming that we never went to the Moon. What do you expect to do? To say "Bravo!"? I was angry, too. And that's why I told him that he's a nut and a narrow thinker.