I am not surprised by any of this account except one: Why is someone known to be mentally deficient 'teaching' the Bible to anyone(granted, we know that the WT literature has little to DO with the bible, but ostensibly, he is supposed to be teaching someone????)? I don't want to be unkind, but the depth of their teachings is amply demonstrated by this account. Paper cuts are deeper if they have a mentally challenged person doing bookstudies.
My mother and others I know are of normal intelligence and they can't begin to answer any challenging questions. I guess the elders assumed that a 14 yo kid won't have any? (I was 15 when I challenged them, so they shouldn't be complacent and assign retarded people to kids!)
Personally, I think if the person they are studying with has any brights at all, the JW study conductor needs to at least be bright enough to deflect-since that is really the core of their religion-deflecting what the Bible says.