The JW parent organization understands the illegitimacy of using logical fallacies in arguments.
A very decent article appeared in the May, 22, 1990 issue of Awake! that briefly described five common logical fallacies and why they should be avoided.
The three fallacies I listed in connection with blood have all been rejected by the JW parent organization in other contexts.
In 1980, they decided that organ transplantation did not constitute cannibalism. In so doing, they rejected the argument of equivocation. Donated organs and tissue "taken in" via transplant need not be viewed as having been eaten even in principle.
The JW parent organization also rejects the argument from silence in deciding medical issues since it is self evident that the Bible cannot comment directly on things alien to its historical context. Medical questions that the Bible cannot and does not address have often been considered in JW literature:
Artificial Insemination -- Awake! August 8 1974
Organ Transplantation -- The Watchtower March 15, 1980.
In-Vitro fertilization -- The Watchtower June 1, 1981
Bone marrow transplant -- The Watchtower May 15, 1984 .
Autopsy -- The Watchtower April 1, 1987
Autologous transfusion -- The Watchtower March 1, 1989
Post-exposure vaccines and serums -- The Watchtower June 1, 1990
Vaccinations -- The Watchtower October 1, 1994
Not one of these issues was decided by the Bible's silence. -Quite the contrary, the Bible's silence is what opened the door and made these matters of conscience within the JW community.
The JW organization also rejects the fallacy of generalization. An article in the June 22, 2000 issue of Awake! explained that this is actually a common propaganda technique that is used to lead people to a conclusion that is not necessarily true. Even if we overlook that fact, the JW organization also recognizes that the symbolism of Christ's blood was transferred at the start of the Christian era to the sacrements of communion (i.e. The emblems of Memorial) Wine and unleavened bread were the new symbols. Animal sacrifices no longer had any sin atoning value at all and no longer symbolized the blood of Christ. Without that connection, this generalization is baseless to begin with.
It is perplexing that what the JW organization recognizes as flawed reasoning in other contexts is used when the subject of blood comes up, but that's unfortunately just the way it is.