For the reasons listed by other players already Dale, I think it would be a very good idea to put a message on the menu screen about this. (It's been done before, sorry but I can't remember the exact circumstances - think it was some insurance related bug maybe a year ago?) Failing that, an in-game inbox message would also seem like a very good idea.
Putting it on the forum reddit and whatever other social media channels you use is fine but a message in-game will be seen by everybody who actually logs into the game over the next week which is surely going to reach more people? It would also probably save support some time in dealing with reports from people who haven't picked up on this through social media channels.
Dale, Red is on the right track; advise people logging into the game and by message that if they don't want PvP due to PP then THEY have the option of un-pledging. They will have been warned and hand holding is not necessary.
This one really has my goat