Merely enforcing "namespace collisions" implies you could still pretend to be anyone who isn't verified on Twitter. The concept of verification is itself a demonstration of a deeper problem with either Twitter or society, but if you are going to do it it has to mean something, and if you can change your name once you do it it doesn't mean anything anymore. If you want to change your name to something silly for frivolous reasons, here is a simple solution: don't expect to also be verified.
