Tl;dr: A forum owner grants a request by a forum admin to transfer their powers to a second, dedicated “admin” account who now maintains a normal account for day to day duties. This plugin would allow the user (the normal one) to switch into the admin account when needed (to perform admin duties). This fits in with the principle of least privilege by only granting the user the tools they need for their day to day work and elevating priviledges when required. The user list is hardcoded in the source code (if I can get it working someday I may be able to consider a onsite setting somehow) and therefore this restricts abuse to those who are able to change the source code and rebuild the app.
This is a potential usage case I can see.
Say you have 1 person (for the purposes of this text his name will be John) and 2 users (for purposes of illustration we’ll call them John and JohnAdmin).
John does not want to be logged in as admin by default for whatever reason (e.g. the default admin ability to override category specific ACL’s, modify groups, change settings etc.). Therefore he has created a second email (or aliased it to his main email) and used that to create the JohnAdmin account. That account is admin and has a randomly generated password that will almost never need to be used.
John is just a normal user. Therefore the plugin’s intent is to override any restrictions on the impersonate feature so John can “switch” from John into his admin account whenever required. The admin account has the ability to impersonate back.
I can understand that only admins are able to switch back but John is already trusted as an admin by whoever has ultimate authority over the system. He only wishes to separate his admin duties from his normal user duties and the forum owner is willing to grant his request. Why not just fork the plugin (you maintain the source code for your install), modify the relevant lines of code (which are presently not working for me) and add it as a plugin. If you really have a privacy need the repo can be made private and a personal access token (or whatever the Git solution you use has) can be used in a specially built link to clone the private repo.