Never a mistake to get a second opinion if there is still a question. In this case the question seems to be is the dislike of ground handling soundness/ulcer related or just normal for that horse. IMO thats a good reason if there is any doubt on buyers side.
Scoping may be relatively easy but is invasive and requires sedation and this horse has already been invaded, poked, prodded and sedated. Glad this worked out the way it did.