Buyer is obviuosly unknowledgeable about the variety of detail in guitar construction, as I was when I joined here, even though I'd been playing for 40 years.
I'm going along with you on cutting buyer some slack because of that.
Never realized there were many nut widths out there depending on maker and vintage until I saw it being discussed here.
Only knew classicals were a lot fatter and flatter.
First time I realized there were standard neck profiles was when I saw a diagram in the 2001 Fender Frontline catalog that I'd never noticed before, ad the light went on about why my Corona D40 felt like ti had stiffer action than my Westerly D25 even though all the set-up specs and strings were identical.
So, suggesting that in addition to nut width you can mention the "profile".
Serious players like the ones around here can then make their own judgement.
For uneducated players like the current buyer, all I can say is try to make sure they understand what they're getting into with some pro-active questioning if you sense any "weakness" in their experience level.
Neck profile diagram: