I can’t really think of a reason why this isn’t offered by the OrderedCollections package. There are in-place sort() (see the documentation) methods for this, so the behavior is well-defined. The only thing I can think of is that it discourages unintentional copies of the underlying buffers, but that same argument would apply to the collections in the standard library and that doesn’t prevent it from having these methods.
So is there a reason I’m not seeing? Or is this just not (yet?) implemented?