it would be nice if at discussion board topics list (and any other lists where this also applies), could define at webpart properties that we want a specific sort order to be applied to pinned items.

 If that value was set, then it would override (only for the pinned items) the current sort order selected by the user.

That way our pinned items would show always in the order we want (e.g. if we have them named as 1..., 2.... etc. and want to sort them alphabetically in that order at the top of the board).