Public Mobile does not have an official "port protection. However, many of the publicised port-out scams were the result of the scammer calling the service provider and using social engineering to convince the customer service rep that they were the account holder.
I guess one assurance with Public Mobile, is that since there are no humans to call, and all support is done online, having a long, unique password, and a trustworthy e-mail service linked to your online self-serve account, you might be less vulnerable than some of the example cases at the premiere brands..
I don't think this will help at all since the person doing the fraudulent porting deals with the company they are trying to port the number to, not public mobile staff. So the "social engineering" risk is the same at PM. At PM you are probably more at risk because you can't call someone immediately to stop the port. At least it sounds like reporting your phone as lost or stolen in your account can stop this if u do it in time.
I think a solution the phone companies could implement would be to send the text saying a port was requested if this was done by u reply Y if not reply N.