If you want someone to moderate the server whilst admins are not online then this is not needed. There will be no real admin to keep an eye over them. If the player is trusted enough to be left alone as a temporary mod, then they may as well be made into moderators and they will be.
This is true, but if there were a temp mod system then you could test people for this status instead of how it's done now, and you may be surprised sometimes for better or for worse.
They can still be tested by making them moderator the normal way. If it doesn't work out then it's easy enough for them to be downgraded ingame or by doing a simple database query if they leave the game.
You should know that levels are set after an administrator discussion, some admin may promote someone because they've seen the good side of them, but their may be a dark and nasty side or just a personal difference in the team which is why discussion happens and why only management can set levels.
If you want more mods then it's management that needs a poke. Not the script.
In this way(what you do right now) you are only going to make your e-friends admins or mods or w/e, you wont give a chance to ppl that is not your e-friend or something, thats just wrong, if the player is good enough, has played for a while, and follow all the rules, then why dont giving him a chance?, you dont give mod to any1 since ermm ? may? thats quite a lot, and there are no new admins or mods, we look the same ppl, and it gets boring, every1 might have their own way to give lw's some fun, ( events, special races, be active to ban cheaters, etc) and i dont see this for a while ( 3 months?)