I think the book Blood on the Altar, may have a misquote (or maybe it is just me reading it wrong).
P. 41, para. 1:
"Pastor Russell took the place of Mr. Barbour who became unfaithful and upon whom was fulfilled the prophecies of matt. 24:48-51..."
The book give the reference of the Zion's Watchtower July 15th, 1879, p. 8 (http://jv.somet.dk/tekster/WT_1879_07_01.pdf). I didn't see any evil slave reference there. Is the author of Blood on the Altar quoting Rutherford's later view?