abray, why post that load of bs when all anyone has to do to refute it is look in the two small source files of the plugin? Or just search for the string 'meta' to see that the two instances of that string have nothing to do with meta redirect or meta refresh tags.
That said, there is a real problem with this plugin if you try to use it when you upgrade WordPress. If you deactivate the plugin when you get to the step of deactivating all plugins it is no longer working of course. But if you leave it activated so the site in in maintenance mode until the upgrade is completed, when you update the source files and try to go to the wp-admin page you are in trouble: Maintenance-mode says that it blocks access unless you are logged in as an admin. But upgrading logs you out, and maintenance-mode has no provision for logging back in as an admin user.
That's a bug. The fix would be to have it make an exception for the login page. But the plugin's website says that the author is no longer maintaining it.
When I got stuck during an upgrade the easy workaround was to edit maintenance-mode.php to change the return statement in the function mw_current_user_can_access_on_maintenance to always return true. That let me login as an admin user again, at which point I was able to deactivate maintenance mode, edit the file back again, and then deactivate the plugin until I or somebody else can fix it properly.