I wonder what kind of bettor will have the heart to spend money earned from betting on people's misery. If a bettor bets on increased death rate and the death rate increases, his/her earning could be considered blood money. Better not to reward that kind of prediction..
Prediction market has to Moral
Well, you do have a point when it comes to moral things but people who do bet into those increasing deaths wouldn't really be taking this as a serious issue when it comes to moral aspects.
This is just business and as long they can make money with it then it wouldn't matter but lets not hope for those increase of deaths.