I'm assuming that he answered that way because he wanted to avoid falling into a potential trap if he gave the honest answer. Which should be embarrassing for him and the GB. Don't they teach that JWs must be ready to give a truthful and faithful testimony, even in the face of persecution or at risk of their safety? When given a chance to do so, Jackson slapped his fellow GB members across the face by calling them presumptuous, lol.
The sadder thing is that the others are not offended by this. They know why he lied and they support it, even though they would threaten rank-and-file JWs with disfellowshipping if they were to act so cravenly as to deny the authority of the GB.