The bible prohibition on blood was dietary and had to do with God allowing humans to eat meat but to keep in mind the significance a life including that of an animal. The act of pouring the blood on the ground was not due to blood being unhealthy but to outwardly show the animal's 'killer' as having respect for the life of the animal.
Whoa! That's way too much common sense for the average JW. That sort of logic has no place in the JW universe. You are going to have to dumb that down a little. A typical JW will cover their ears and keep repeating " It says abstain, It says abstain."