The 1992 article is really the only article ever to attribute the GB helpers to the Nethinim. What's interesting is that the 1992 article said that the Nethinim were never considered equal to the Levites. One of their references was the Dictionary of the Bible, and when reading that source, it later says (but not quoted by WTBTS) that the Nethinim later became indistinguishable from the Levites. This was one of the first places I noticed intentional misquoting by WTBTS.
The WT article says this:
16 When the group returned from Babylon, it contained few Levites, compared to the priests or Nethinim and “sons of the servants of Solomon.” (Ezra 8:15-20) The Dictionary of the Bible, by Dr. James Hastings, observes: “After a time we find [the Nethinim] so completely established as a sacred official class, that privileges are accorded to them.” The scholarly journal Vetus Testamentum notes: “A change occurred. After the Return from Exile, these [foreigners] were no longer regarded as slaves of the Temple, but as ministrants in it, enjoying a status similar to that of those other bodies, which officiated in the Temple.”—See the box “A Changed Status.”
17 Of course, the Nethinim did not become the equals of the priests and the Levites.
The Dictionary of the Bible says this (page 654):
From this point the Nethinim gradually rose in official position, until they were Indistinguishable from the Levites.
Another interesting thing is that the revised NWT no longer says "Nethinim". Each place where that term occurred in the old NWT, it's been replaced by "temple servant".
The term itself was first applied to the Gibeonites who tricked Joshua (see Joshua chapter 9).
For WTBTS to apply this to the helpers to the GB was and still is way out of line. If they want to have helpers, fine. But don't say these are "given ones" or "Nethinim". The two terms have nothing to do with each other.