It's been long-standing policy that you need First and Last Name to post in TPP forum.  It is possible to lurk in TPP without your full name, if you don't post.  Once you post, it's just a matter of time until you get caught.

If you go and update your profile to include your full name, that does not automatically allow you back into TPP. You will need to go to the FAQ's and Support forum and request to be allowed back in. And asking to get back in is no guarantee that you will be let back in.  That's the way it works.