I don’t think someone needs to be an expert to represent a car for sale, but if you have access to the expertise, as he does apparently, you should take advantage of it. At least double/triple check that the numbers on your mid 6-figure car are legitimate. I think it was a pretty big oversight not doing that immediately when the car showed up. While better than many, it’s obviously not a factory stamp and there’s no machining marks on the flat. There are lots of photos on BaT which have been compiled since 2014 of what factory block standings should look like so it’s not like you need a divining rod to decode what’s in front of you.
All of that said, it came up early enough in the listing and he handled this much better than some sellers would. They have potential to be out a decent amount of money with acquiring the original block, building it and shipping it to the buyer. Of course it could also pay dividends but we won’t know any of that until the final 2 min.