You can conclude that he wasn't really endeavored to be personally honest but rather faithfully more devoted toward the Watchtower Corporation,
which he held the position as the head editorial writer as vice president and president of .
Actually the 6000 years of man's existence was once before used by the WTS. back in the early 1900's to support the New World organization theory.
I was surprised by this bit of information myself. My own guess to why he pursed this 6000 year thing again is it had becoming apparent to him
even back in the late 60's early 70's, that Generation who witnessed the events of 1914 were dieing off with nothing much happening to support
the great tribulation doctrine. So he made a kind of diversion to take this realization away and out of the minds of people who were querying upon it.
Of course the capability of calculating the length of mankind's existence on earth, no less to October of 1975 is quite the lying pretentious fraud
of grander, for its impossible to accurately make that calculation from the bible or any other documented archaeological means.