The only motive I can see for doing this is to get press and sell it for a reasonable amount. A couple was arrested last week for trying to auction their baby on ebay. Some kid tried to auction off his virginity. These things make the papers. If a news agency picks it up, he may have people come at him with more reasonable offers. I would expect that the value of something like this is more in the range of $10,000 (although it is not worth even that amount to me) than $2.4M.
Given this, I cannot expect that he is that stupid to think that anyone would pay close to this amount. As Planahea mentioned You could buy half of a Gutenberg Bible for this price.
J.K. Rowling got $3.8M for a handwritten Harry Potter manuscript, but then she is just a hugely popular bestselling author and Leary is a minor author and this is a minor work of his (and is an excerpt). Plus, Rowling donated the money to charity. A crafty accountant can probably get away with taking a deduction on the purchase for some of the money as it was so high over the expected sale price. It can be assumed that part of the money was a direct donation, while they received a product (the m.s.), it was not worth $3.8M.
If there is a rich guy stupid enough to spend this kind of money, then there is really something wrong out there.
p.s. I am not a Rowling fan, I'm just sayin....