Or maybe Charlie just thought the 8Cs sounded too thick to his liking. If I remember it correctly from that thread, he said he thought the Dutch speakers lacked the sparkle at the top which he liked about the Genelecs.
The thing is that he may not have spilled all the beans about why he didn't go with 8Cs as you as the dealer were there, he may have said things more politely because of that, which I think everyone would have done in that circumstance. It's perfectly possible that he would never even have tried them out if a close audio friend, who knows the in-and-out of why he likes his Genelecs, had said he wouldn't think the 8Cs would suit his reference of a more sparkling-sounding top end or something similar to that.
Yes, all that is just speculation, but you as the dealer who had gone the extra mileage of a home demo may not have heard the real reasons for the customer not buying the speakers. Just saying.