I don't know... the Giant I bought from Tremper sure was a defect.....
Actually I do have to agree, Giant still could potentially be a defect.....
In fact the seller is right, most leopard gecko morphs would be negative in the wild.
However none of the morphs are negative in captivity. None of the morphs are health risks. Dwarfism is a health risk. I do not want to think of what would happen to a gravid dwarf... but who knows, it might be fine.
Nonetheless, I see nothing desirable in a Dwarf trait that would make it worth the inherent risks....