To abstain from blood was to abstain from eating meat that was not bled properly.
All meat has blood in it, its not the blood but the ritual cleansing that is the act of obedience.
The illustration about alcohol is both a red herring and straw-man as it does not accurately follow the premise
if it were somewhat apples to apples, the illustration would be to avoid alcohol in excess but of course this would not support the WTS position