How does this play out? An intellectually honest response would be along the lines of: “Okay, your argument seems to check out on first glance, but I’m rather skeptical that it’d hold up if I spent enough time thinking about it. Anyway, supposing that it was true, why should the real world be anything like A?”. This is much more honest than simply trying to dismiss the hypothetical by stating that A is nothing like reality.

These are the long and the short version of the same thought.