The only place it gets close to relating it to Witnesses is in the Insight book under "Love":
One’s Love Can Cool Off. Jesus Christ, in telling his disciples of the things ahead, indicated that the love (a·gaʹpe) of many who professed belief in God would cool off.
Yup, written completely ambiguously.
Many who professed belief in God - could be "weak" JW's, "Christians" "theists," etc. etc.