It's unfortunate, but he's not actually trying to scam anyone. He truly believes that he invented email. Furthermore, he has become paranoid in the belief that there is a huge conspiracy to discredit him.
Consider replacing "actually" with "intentionally"? He's actually trying to sell a lie. Whether he knows it's a lie might be another matter, and I'll grant you the benefit of doubt around his delusion.
So I don't entirely think that the teller of the lie needs to believe that it's a lie for it to be a lie. If they believe it, it just means that they're deceiving themselves as well.
Aside: Interesting to reflect on how Google's past domain keyword preferences allow grandfathering in of domain authority.
Go to Google and ask it "who invented email".
Interestingly, Bing gives a different answer.
I mean he categorically did not invent email. My friend Dave Crocker was involved in the birth of email and this guy was not participating in that process. it was created before his invention. It's just a lie.