The article (Watchtower July 15, 1952 page 426) continues to identify two classes among the Lord's people.
I haven't read the whole article, but here I do not think the WT is talking about the two-tier salvation plan Russel invented. It could be JW's vs. all other churches. But, I think this is referring to the JW's who stayed associated with the WT corporation and the ones who left after Rutherford wrested control of the WT legal entity.
The article goes on to say: "So they, together with their hay, wood and stubble, perished as far as Jehovah’s organization was concerned. If they had let go of these things they might have been saved."
In my JW family these people were referred to as "THE evil slave". I can still hear the whispers in the shadows my aunt would make about the "evilllll slaveeee" with a slightly contorted face. (Think of that look and whispers an older Sicilian woman might make in a movie when speaking of the "evil eye curse", becasue that's how she would say it.) Absolutely bone-chilling to an 8 year old.
Russell invented the two-tier salvation heresy in an attempt to shut up the kingdom of heaven . It has been one of the more successful attempts to hide salvation from people..