As usual, technical people easily miss the marketing value of sound bites. He should have invented a clever and catchy story about the first email.
Technical people will immediately say that you can't do that because that would a lie, forgetting the thousand "lies" that we are all complicit in (Santa Claus, tooth fairy, "your tie/haircut looks nice", "sorry, I don't have any change to give you").
EBay founder Omidyar said that eBay was invented to trade Pez dispensers, a story he's now admitted is completely false, but no one seems to be too worked up over that. Apparently Omidyar understands the difference between a lie (has an actual negative effect on someone) and marketing fluff (makes for an interesting story but is just trivia).
For such an influential person--in the sense that he had a huge impact on the world--Tomlinson is completely unknown. I'm guessing that his financial reward for inventing email was essentially nothing as well.