In 1931, wts followers already knew 1925 failed so why pursue a failed prophesy and bring a spotlight to this crazy idea?
Huxley described this. They have been conditioned to accept facts without processing them, a facet of Cognitive Dissonance. Thus they were not conscious that the prophecy had failed:
At breakfast the next morning, "Tommy," some one says, "do you know which is the longest river in Africa?" A shaking of the head. "But don't you remember something that begins: The Nile is the ..."
"The - Nile - is - the - longest - river - in - Africa - and - the - second - in - length - of - all - the - rivers - of - the - globe ..." The words come rushing out. "Although - falling - short - of ..."
"Well now, which is the longest river in Africa?"
The eyes are blank. "I don't know."
"But the Nile, Tommy."
"The - Nile - is - the - longest - river - in - Africa - and - second ..."
"Then which river is the longest, Tommy?"
Tommy burst into tears. "I don't know," he howls.