steve2,
There is another more specific historical and doctrinal reason why some JWs are apprehensive about giving testimony under an oath to tell the truth.
We all heard Toole claim ignorance to Watchtower's Theocratic War Strategy (TWS) question. (Sideline: Toole said he had not read the 1950s era Watchtower addressing this in detail since he was baptized in the 70s. Unfortunately the RC lawyer was apparently unaware that in the 1980s there was a Watchtower article citing this doctrinal position, and presumably Toole would have read this and at least wondered what that term meant.) So, getting back on track, Toole denied knowledge of TWS as a doctrinal position. But it turns out there is a peculiar twist to Watchtower's TWS doctrine. That doctrinal position EXPRESSLY allows outright deception by knowingly giving false information but just as EXPRESSLY it prohibits giving false information if the JW is under a sworn oath to tell the truth. Older JWs are certainly familiar with this, and as a practicing JW attorney Tools should be. So, a JW can be intentionally dishonest in order to 'protect the interests of the kingdom' UNLESS he or she is under a sworn oath to tell the truth. THEN the JW is prohibited from being intentionally dishonest for any reason. In the latter case the JW would have to refuse to answer and face punitive measures accordingly IF they were asked for information that would compromise 'interests of the kingdom' but did not want to give up the information. This because TWS doctrine requires telling the truth when under a sworn oath to tell the truth.
Hope that helps.