Then the good brother cuts him off and exclaims "Are you saying the faithful slave is delaying Armageddon?"
It's actually a straw man argument, in which someone raises a superficially similar proposition and then argues against that, without actually addressing the initial argument.
The bad brother who complained, "When are these last days going to end? I mean, its been over a hundred years and our understanding keeps on changing, and changing, and changing..." is asking a valid question, and a demonstration in which a good brother accuses him of disloyalty is yet another demonstration of crude mind control techniques. In short, it is wrong to ask questions that contain implied criticism of the organisation. Any JW who asks a question that questions the beliefs or practises as laid down by the Governing Body is accused of disloyalty, thus intimidating them into silent, unquestioning submission.
I just wonder how many in the audience heard the bad brother's question and thought to themselves, "Fair point!" and were, like Silent Scream, dismayed to hear the response, which doesn't address the quite sincere question at all.