They appear to be thoroughly convinced that JWs are astoundingly stupid and could not possibly determine the "correct" understanding unless it is pre-chewed, regurgitated, mashed, and macerated into a thin gruel.
Well that's not necessarily the reason for their concern here, and they tacitly acknowledge the problem:
Of course, any answers given by the audience that are appropriate and in harmony with our present understanding are acceptable
The fact is that they change doctrine so damn often that a lot of JWs just can't keep up with it all and fall back on "past truths" that are apparently no longer true.
But there's definitely a fair amount of just genuinely not being able to keep up with the nonsense doctrine without the constant changes. One of my favorite examples was when an elder referred to peter as "the rock on which Jesus founded his congregation" I was in the process of trying to leave so I didn't want to make waves, but I really wanted to let him know that he was parroting the catholic understanding of that scripture but the GB approved doctrine is that Jesus was referring to himself when he said "this rock."