For me this issue is so simple. Blood is sacred because it represents life. Life is so sacred we should do anything to save it. Including using blood to save life. This is actually the most respectful way we could treat blood, to use it to save life. it's what blood is for, to preserve life.
If you take a life, you are blood guilty. If you let someone die because they need blood, you are blood guilty.
The biblical 'pouring out blood' was about killing animals and eating them. It was disrespectful to eat the blood, it was not considering the life that you had taken to eat that animal. It has nothing to do with how blood is used today to save lives. It is disrespectful to let someone die and not use the lifesaving gift of blood.
it is the simple-mindedness of JW doctrine to take these scriptures and not only over-apply them but not understand the principle behind them.