Saename wrote: Sort of true. Whilst there would be no problem if they wanted to use modern scholarship to explain Josephus' and Tacitus' references to Jesus, they would have to deal with certain inaccuracies in the Bible if they wanted to use the Bible itself to "prove" Jesus' existence.
The purpose of the article is to use scholarship, not internal bible logic, to try and prove Jesus existed though. Grant, for example, wrote on Tacitus and was one of many who believe/d that Tacitus' comments about 'Christians' isn't a later interpolation. But to open that can of worms is to introduce the idea that every text can be subject to such manipulation and so every one of those passages by ancient authors they cite must be buttressed against it. Josephus in particular has been subject to later editing, although there's a good case for something there being original to him. To introduce doubt to a world of black and white fundamentalism is what they are very keen to avoid.
So really it's very true that the WBTS' writers seem to exercise great care in the source materials they use because even the case for a historical Jesus opens up all kinds of questions. Perhaps the greatest amongst them being just how accurately something written decades after an event can relate what happened - as that applies not only to every non-biblical source for Jesus but also every biblical source too!