Culturally, it's my feeling that funerals are not for the dead, they are for the living, and this is a way for the dead to cut into the lives of people who now get to move on.
The "zing" element of it is just a way for someone to be hurtful to people who can never have closure on that...
On the flip side - not everyone is cynical, they may say some of the things they had a hard time saying when they were alive, affirmations that maybe made them uncomfortable, or admitting wrongs that may have been too difficult to do when alive.
I'd hope that a service like this would be thoughtful, and pensive, and think of those who are left behind as a primary focus.
Edit: and this is all possibly moot as it sounds like this person isn't even real (I get that this is speculation, but I'm just sharing it because I agree, this story is questionable): https://news.ycombinator.com/item?id=24427464
Edit 2: https://news.ycombinator.com/item?id=24428153
Pretty good evidence this is actually real, so, yeah, my comment stands though :)