This is clearly a compare and contrast piece. He is contrasting what he took from the meeting with what the Developer CEO took from the meeting, with a heavy implication that those benefits were exclusive to each other. He says it more or less explicitly:
"I suspect in his mind the benefit of meeting was directly related to his perception of the quality of data in my answers."
Also look at the language construct used:
"Whereas he based the value of the meeting on the quality of the data I focus on how much I think I got an accurate snapshot of how the person thinks and operates."
The google definition of 'whereas' is "In contrast or comparison with the fact that.".
To possibly overthink social cues, I think that timr wrote a true but slightly condescending response to a slightly condescending article. Since engineers commonly are condescending to sales people, and since HN is filled with contrarians, someone felt obligated to stick up for the sales guy.