I think it means they are traversable rather than your character being able to climb. A man can wish though...
Yeah, talk about dubious staetments (in that article). There's another debatable quote:
(...) When you're talking about a game that also includes dragon-slaying, a freeform world in which you can manually climb to the top of the highest mountain in sight (..)
If ?manually climb? means going up the 7000 steps staircase, then, no,
Climbing is not in.
But it's open for discussion.