a simple topic lock, it works fine for me. it only works for one channel. make sure to replace YOURROOM with the channel you want to protect, then put the topic for that channel that you want to not be changed as ROOMTOPIC (there's 2 spots). yeah I guess it's a noobish script, but it works good if you just wanna protect one channel and don't want some complicated dialog.

on *:topic:#YOURROOM:{ 
  if ($chan(#).topic != ROOMTOPIC) {
    topic #YOURROOM ROOMTOPIC
  }
}