If i'm not mistaken, anope has a method to prevent users from being added against their will already. I see no need to make this complicated by adding a queue. Adding users isn't as complicated as changing hosts or adding botserv bots to channels. That said, i don't have an objection to this feature either. Just really don't think its worth it.
Currently the user turns off the setting, the channel op adds the user and the use turns the setting back on. Nice and simple.