@Jay
No, it's OK to display the PM button, because it forces the person to register, I say, for example:
Peter sells a car, Peter is registered on my site.
Lola is interested in the car, she wants to send a PM, click send PM button, but as it is registered you get a notice "must register to send PM" Well Lola is recorded press PM button to send, but Peter never receives the message, only receives the Admin.
Understand?
I tried the new zip and button does not appear to any person.
This is great work
Saludos
Chofi