Ok this is stupid.

1. It is impossible to tell apart different unregistered users in a thread, making it confusing.

2. This would not be an issue if people just typed in a nickname in the unregistered box (and refrained from impersonating others).

3. If someone flames you just ignore it.

4. You should have a spam email account for registering for services. There are plenty available, even some explicitly for that purpose.

5. When you sign up for email/services keep your personal information as general as possible.