There is a range of Bible Canons and variant texts (Roman Catholic, Ethiopian, Orthodox, Protestant, Old Greek, Theodisius, Masoretic, Siniaticus, various LXX, etc.) emanating from arguments dating from the 2nd century within Judaism and with Marcion and it has continued ever since (especially 4th to 7th centuries CE; Trent, Luther, etc.).
The material has experienced constant change, and the WTS simply follows that well-trodden path when it adjusts the texts to suit its doctrinal positions. This has been happening ever since the first pen was applied to the earliest scrolls.
The WTS adapts the 19th century material by the Trinitarians Westcott and Hort.
No Bible or Canon existed when any of the above cited texts (2 Tim 3:16, etc.) was written, and they are simply propaganda opinions. To assume the (anonymous) writer of 2 Tim was telling the Truth, one would have to assume he had information that came directly from God. In other words, is 2 Tim 3:16 inspired? A circular argument indeed.
To be technically correct, the Greek word at 2 Tim 3:16 rendered as "inspired", simply means "god-breathed". Unfortunately for those wishing to impress their presumptions, it is a unique word with little to help determine exactly what the writer intended -- which at the time would have referred to any of the earlier Jewish and Hebrew writings -- including 1 Enoch, which is so heavily referenced in the "NT" documents.
At that time, there was any number of documents accepted by the followers of Jesus, including several Gospels which were later excluded on dubious grounds. Codex Siniaticus includes Barnabas and references the Shepherd of Hermas.