There should be no awards for killing players apart from the treasure they carry.
I like the concept though.
However how it should be executed should be different imo.
Instead of having it as a choice, make it so that the curse is something that happens to you.
A way to include this is to add some form of treasure that curses the crew when picked up, or opened.
Lets say its a golden idol.
One pirate in the crew finds a random treasure chest and opens it up to find the golden idol, and upon opening the chest, the entire crew is cursed until their next play session.
No shadow, veggie or gold player skeletons though because that would be hard to balance.
Infact one could call it a nightmare to balance.
There could be bonuses for having the curse, such as, health regen over time. (Have speed of food regen)
Bullet resistance
Immunity to drowning
Normal island skeletons ignore the player (except quest skeletons)