Fisherman,
With respect, I don't believe you have bridged the gap between the eating of blood (What the Bible forbids) and the transfusion of blood (What that prohibition is interpreted by JW's to mean in the context of modern medicine.)
You seem to be relying on your own gut feeling and that's not enough. Similarity is not moral equivalence.
There is a similarity between marital sex and adultery, but the two are not morally equivalent acts. Attempting to imply equivalency by lumping them both under the broader category of sex would be the fallacy of equivocation.
There is a similarity between burning a pinch of incense to a pagan god and burning a pinch of incense because you like the ambience, but the two are not morally equivalent acts.
There is a similarity between sipping wine during a JW memorial and sipping wine after you get home. (Even if it is poured from the exact same bottle) but the two are not morally equivalent acts.
Even strictly within the scope of the Decree, there is a similarity between the eating of an idol sacrifice in a pagan temple and the eating of an idol sacrifice when it is sold to the public, but the two are not morally equivalent acts.
Moral equivalency is not established by similarity. It is established via a logical construct.
Try a simple thought experiment. Why does the prohibition against murder, expressed poetically as, "shedding man's blood" apply to poisoning, electrocution and other forms of murder where no blood is shed? How would you construct a watertight argument that would stand up to criticism?