Also, if you have nothing to hide, why would you sign a non-disclosure agreement?
So many red flags.
But I am not going to pursue this any further. I have drawn my lessons, others are free to draw theirs.
ETA: In parting, I wanted to say that I have studied the work of Mr. Zacharias and it has helped me a lot. I am grateful for his contribution. However, he is still a human being and as such, he can disappoint and fall short of expectations. The only one who will not disappoint us is God.
God does not expect us to never sin because He knows our sinful nature. I think what is expected of us is confession of our sin and sincere repentance. From then, we can ask for forgiveness and resolve to not repeat that sin again. I did not see that kind of unflinching honesty and humility in Mr. Zacharia's response, and it bothered me. But it's between him and God so I am moving on.