Goneforgood, i don't know if this is what you are looking for, but the following quotes give some historical background, and substantiates where the idea comes from that being inactive means that a person is no longer a JW
from Preparation by Judge Rutherford pg 326:
Jehovah does nothing toward the destruction of the enemy in secret. His faithful witnesses must give this warning in the name of Jehovah, and their failure or refusal so to do would be evidence of their unfaithfulness and lead to their own destruction.
and from Theocratic Aid to Kingdom Publishers, 1945 - pg. 8:
It is discretionary with an individual as to whether he will serve the Lord, but, once having made a consecration to do God’s will, obedience to Jehovah’s commands becomes mandatory. It is a matter of life and death.
You can find both those publications here:
http://www.jwfacts.com/watchtower/historical-publications.php