PPC member (or just PPCer) is a tricky phrase, because, while in many cases one will automatically think of the agents of the PPC, the Boarders are equally PPC members, too.
As stated by CAL-9000 (and a possibly confused Mortic Wentway) in the third Playscripte:
Cal: As I was saying, we discovered that the cause [of the power failure] in that instance was a group of members of the PPC visiting [Tolkien's] grave. The concentrated presence of so much Canon Love apparently counteracted the effect of the Badfics, at least temporarily.
Mortic: Members of the PPC? You mean agents did this?
Cal: Not… exactly. The Protectors of the Plot Continuum has developed something of a fandom of its own out there in the World, and it was a Gathering of these fans – members of the 'PPC Board', their internet meeting place – that caused the disaster.
Be warned: Just because you are considered a member of the PPC, it does not mean you can go and flamethrower flowers. For one, your neighbors will be upset at what you've done to their gardens, and two, people will be wondering where you got that flamethower. Only actual agents can get away with it, sadly enough.