To join PMO, use the "Contact Us" link at the bottom of the site to write to me.
I routinely approve new member accounts for those who write to me using the "Contact Us" link at the bottom of the site. From time to time, I may approve new registrations for those who do not write to me but happen to register while the registration link has been made temporarily available for those who have written. Registrants who have been admitted without writing to me will have their content moderated (hidden) and their personal messengers disabled until I am satisfied that their posts are not spam or otherwise objectionable. (It should not take long to make this determination.)