Saying "He’s talking about whether agents are currently useful at all" is negatively loaded. It is very easy to take that and assume the answer is "no" based on the "at all".
If you wanted to be more neutral, you could have said something like "He's also questioning how useful agents really are today". That wouldn't have implied that they're not useful at all, but instead that they're less useful than people are claiming.
That question doesn’t do enough to highlight how wrong the OP’s interpretation was. He’s going far beyond just stating that agents are less useful than people are claiming. Less useful than people are claiming fits the OP’s interpretation.