1975 wasn't presumed by the witnesses, it was presumed by some witnesses who based their life choices on rumors and hearsay rather than what was written, and they were weeded out
oh good...thanks for clearing that up. i was an active jw in the late 60's / early 70's and i can assure you it was anything but rumours or hearsay..although a lot of dubs did take it to heart and planned their lives and finances on it .
As for being weeded out--the district servant who spoke openly about 1975 ended his career at watchtower HQ in the UK.