Couldn't agree more. My first step when troubleshooting anything for someone else is to extract as much information as possible to understand what I'm dealing with. Having that information from the start would save me a lot of time.
>I can't say I perceive the dismissal from the quote alone.
True, the quote alone is not necessarily dismissive or arrogant, and your interpretation could very well be correct. I'm assuming it was dismissive because the author seems troubled by his own response, which he interprets as "I just told him that he's wrong and he doesn't know what he's doing". That's where my interpretation comes from.