Users are normally approved from the "Approval Queue", but if you click into a user's profile to check them out in more detail it kind of dead ends you right now. I've occasionally hit this myself, and think this workflow is generally reasonable enough to support upstream.
Maybe also (or alternatively) check for $is_admin and visually call out the "Not Approved" text in the header of this page? Or in the "Roles" property farther down the page.
I also thought about putting a standalone "approve / reject" panel on the main profile page (not the "Manage" page), but I sort of want to modularize that at some point (so we can get a "member of instances: x, y" panel on admin.phacility.com) and don't want to make that any harder than it already is until that happens.