Thank you! She is quite a sweetheart. 
I get the impression the seller knows exactly how to measure, but feels height is unimportant. She regularly shares stuff like this post. (To be clear, that’s not the seller, just a post about height that was shared by a whole lotta people!) And the horse is young, she may still grow some.
But I sure wish I had been given the opportunity to decide if I wanted to roll those dice, instead of that decision being made for me! If the seller had been honest, I may have still moved forward. Maybe not. But buying a horse that’s the height I want is a hell of a lot more of a sure thing than hoping they still have a few inches in them. 
There just seems to be this trend of sellers disregarding or ranting about what’s important to buyers? And I guess maybe that’s always been the case, but social media is such a wide reaching platform compared to complaining to a few close friends. If our demands around screening for lameness or spinal abnormalities, or desires on height or other physical features, or anything else, are really that onerous, sellers could, idk, limit PPE availability, not allow them at all, offer only a general height assessment, etc, etc. Maybe that would help out everyone by just setting expectations up front. Sellers get the type of buyer they want, and buyers who find those things important can move on to sellers who do, too.
@beowulf I don’t want to share anything identifying publicly (trying to keep this vague as it is, lol) but I’ll send you a PM 