There’s a workaround: if you use Window > Sort By > Content Length Ascending/Descending, it will sort the tabs by content length, which also sorts the Document List.

Because that sort feature exists through a different menu, it’s not likely that the developer would add it to the Document List panel as well (and it’s guaranteed that it won’t happen if you only have a post here, because as our FAQ explains, this is not the place for feature requests).