I'm not sure of your location but I have no idea what coir is. With all the names for the same stuff that we use, like coco husk and coco fiber which I call eco-earth or bed-a-beast which comes in a brick and when exposed to water it expands. That's what I use and like especially for tropical species. The important thing about emperor's is to make sure they stay nice and humid.
As far as your Emperor dropping dead, the bad thing is when you buy an adult scorpion from the pet store, you have no knowledge of how old it is, so it could of been getting ready to die or could of just turned adult. That's why we should always work to establish captive bred scorpions and it's why I keep track of my scorpions and when they're born.