It should be possible to make ?showcurationtoolbar=1 and the 'curate this article' link work on any article, not just those in the feed (but currently can only be used on articles that have not expired out of the NewPagesFeed).
It is quite annoying that the Page Curation tools are only available for new pages that haven't expired, it means that I have to use Twinkle whenever a page has been reviewed and expires out of the feed.
It silly that the Page Curation tools are only available on new pages and not, for example, on Broadwater Green. IMO the 'curate this article' link in the toolbar should always be available to New Page Reviewers.
Note that the page curation tools should ONLY show up on 'other pages' (pages that aren't in the NewPagesFeed) if that string is added to the URL or if you click the 'curate this article' link. Otherwise I think people would get quite annoyed with it showing up on all sorts of other pages constantly.