This is absolutely pinned. I prefer to imagine that since we haven't noticed such comments on the regular means this power is not habitually abused to float a particular opinion/angle to the top of threads. That policy is not guaranteed to be enforced, so I'd prefer a visible indication (eg. via an icon, akin to Reddit) indicating the comment has been pinned. Transparency for the win.

Of course, a truly Evil™ company would have both options available: a visible icon for transparently pinned comments, but also the ability to invisibly pin a comment to influence readers. There is no real foolproof method, unfortunately.