Consider that the shop is unlikely to have the laptops stored or annotated by box size.
Dan was asking the employee to expend considerable additional effort to find the smallest laptop box when he potentially knew the model number, or least had a reason that would justify the extra work. I would have just said "I'm really tight on carry-on space", not to avoid looking stupid, but to assure the employee I wasn't breaking their balls for no reason.
He touches on this later in the article after comparing thoughts to another person (who is block quoted) who seems to wonder the same things as a lot of commenters here...
I would have synthesised a brief approximation of the real reason. Transport being one real possibility.
The point is that this is a two way transaction with a real person, who has their own hidden state, goals and limits that are not always apparent to a consumer.
E.g. company policy on deducing what the customer really needs.
How was the employee to know Dan was the one person who actually knew what they needed, out of 100 over confident buffoon's that came to the shop that week.
This is why I don't hassle the support person fixing my internet when they run through support script.
I don't say "skip this, I have an honours degree blah blah", cause they have enough constraints to deal with as is... And once in a 100 times, I will learn something I didn't know...
IMO, falsehoods do not constitute dishonesty anymore than truths constitute honesty. Honesty is about the sharing of clarity, and sometimes teachers Lie To Children¹ and other times people confuse or obscure with facts. What matters is a sensitive understanding of what clarity means to others.
Anyways, if you tell a store person "oh, I'm getting this for my husband" when it's a gift for yourself, that's more honesty than dishonesty, because to the store person, "clarity" with a customer is very goal oriented. Dan Luu wasn't trying to screw with the store person, and in the end they all got what they wanted, even if Dan Luu walked away "looking stupid".
Dan was asking the employee to expend considerable additional effort to find the smallest laptop box when he potentially knew the model number, or least had a reason that would justify the extra work. I would have just said "I'm really tight on carry-on space", not to avoid looking stupid, but to assure the employee I wasn't breaking their balls for no reason.