I don't know if you sensed it, but both hajrice and Xavdidtheshadow were sarcastic in their posting :)

At least what I take from it, good CEO would answer you with "thank you" or whatever, as Benioff is know to be more of a Ellison / Jobs type of asshole CEO, rather than let's say polite Elon Musk, so hajrice made fun that instead, Benioff asked him to buy his book in order to just squeeze few extra bucks from someone that admires him :)

Xavdidtheshadow was pointing how creepy it is to get forced to receive someones book with their signature that actually is being signed by someone else.

Both their responses made me laugh, thanks guys :)