That would not solve the problem, it might only alleviate it slightly by initially slowing them down or preventing direct cross-region spam.
The reason is because the bot spammers do not necessarily need a search list, they can just stand idle at some place and get the name of any player passing by in their radius which is bigger than normal visibility or line of sight (the game client knows more than what the player sees on his screen and bot software usually have access to such informations). So this would just force them to teleport and eventually run around as well, instead of spamming everyone from the same place but they can automate that easily.