Or google cognitive dissonance and confirmation bias.
This isn't cognitive dissonance. The man simply didn't want to get into it. Cognitive dissonance is a subsconcious conflict. I would wager this guy doesn't have any conflict, subconcious or not, about whether or not Jesus is God. Especially since the NWT pretty much does away with that doctrine as it was "translated."
The real issue here is his devotion to the NWT's teachings without verifying the NWT's authenticity.
-Sab