FM, I don't think Lee is ignoring the base scriptural reference to blood. The point is that the WTS has not actually stuck to their original position on this scripture. When the policy was first implemented you just had whole blood transfusions. Whilst the relationship between eating blood and intravenous delivery can be argued, at least the position was consistent with a simplistic interpretation of scripture.
With the advancement in medical technology the lines have become ever more blurred over time. Instead of sticking to their position they have muddied the waters by allowing the wide use of products obtained by processing donated blood. It is impossible to back up what actually is permitted with scripture - what is acceptable or not acceptable is simply down to the whim of the GB.
There are a mass of inconsistencies, illogical arguments and nonsense surrounding this policy which are conveniently ignored by the faithful simply because they are indoctrinated to accept the ramblings of the F&DS.
Why have the Witnesses got themselves in this mess? Because they are stubbornly holding onto a policy for no other reason than to keep the lid on a legal Pandora's box were they to say they were wrong and remove the prohibition.
To that end it is and organisational policy. Sure, it has a history in scripture but policy and scripture are so far apart now it's ridiculous.