this whole part of the Blue Ridge Parkway is tagged with
The ors will therefore use a speed of 5 km/h to route there (source).
This leads to the travel time of about 2 hours for roughly 10 km, which checks out.
I would agree that using 5 km/h for routes with
access:destination is questionable. I have opened an issue about that, if you want feel free to discuss there.
However, I doubt that this is the correct labeling for this highway.
It was introduced about half a year ago, the reason being that the Blue Ridge Parkway “is not a regular means of travel for commercial vehicles” (compare this changeset).
If you are from the area, maybe you know something about legal restrictions for the highway (in form of a physical sign) and could comment on the tagging some more? Compare the osm wiki on usage of