They can appear registered but that is if people have the time and effort to actually register it... If you don't do email confirmations then you need just remove your network and be done with it because it's definitely waiting to be hit. It's not perfect, no, but it's the best thing that's been made so far.

The problem is lag... if you check the /who on a nickname but you have around 20-30 nicknames alone with hundreds more connecting... it'll really put a strain on your connection & probably flood you out. That's the only problem so you need to create some filter that counts the number that join at a period of time then pauses on a timer to ban the rest OR you could possibly ban range IP/hosts unless there's a large amount of IPs and hosts being used...

So no, it's impossible for a 100% working anti-drone script but it can be done to filter most out.