There are some situations where neither the page creator nor the last editor of the page are the relevant people to notify of a page expiry. Similarly, the space admins and supervisor may know who the current owner is, but have to manually notify them of expired pages.
If the person who currently owns the information on the page is known, then there should be a way of indicating who it is. A way to do this that fits in with the current design would be to apply a label of the form: owner-[single-]<user>. This should support multiple owners being defined for the page.