Is that actually a Tenshi? My first impression was that it was just a decoration, not a yukkuri. If it is an actual yukkuri... yeah, I'm not sure if sitting on a sharp wedge and liking it meets the wiki standards for violence or torture.
I think torture, at least in this context, refers more to the nature of the act, not the outcome... This is the same kind of "torture" that you'd find in an S&M scene (which is the whole point), yet that is thought of as torture.