Meanwhile I have consulted with a member of the SAC working group on the scale of theirs. I learned: In their latest revision, they deliberately changed some terms in the titles of the columns of their scale to make them less likely to be misunderstood. The change relevant to this picture:
Where before the column title read Trail/Terrain it now reads Typical Terrain and Possible Difficulties.
Consequence of that: Trail well cleared is no longer a necessary condition, it is just something people can typically expect from a T1 (hiking in OSM terms) graded hike.
That is why I wrote “Trail with minor obstacles, nothing to warrant anything above hiking.” because that describes what is relevant for grading and can be seen from the picture.