I guess the question … leading all the way up to the OP here is.
Should pinning ignore topic list ordering? At the moment when you look at latest, it sorts pins by bumped_at and then the rest by bumped_at.
Fiddle with ordering on the list, you will impact the ordering of both pins and non pins.
I do feel for this feature request and the change is trivial.
We could unconditionally regardless of topic list ordering, order pins based off “pinned_at” date. We already have all the information and the cost of the change is low.
Advantage from a site operators perspective is that they can easily and unconditionally keep the most important pin at the top. (want something on top, unpin / pin)