It seems a bit strange that as late as 1952 (post-Rutherford) there was still a distinction being emphasized between Russell's time and beyond.
Some time ago I did a lot of reading of the post- Russell literature (both WT and non/former WT) and came to the belief that
much of the dialogue as in the '52 WT quote in the OP were part of a broader debate between the WT-adherents and the
breakaway movements. Particularly the Dawn movements and the LHMM, both of which were led by former Bible Students from the
Russell period and were publishing magazines. It was a sort of intellectual sparring between the WT writers (Franz mostly in this time period)
and the Bible Students (the 'evil slave' as they were labelled by the WT at the time).