This might be a prevention for bots/spammers to create an account and spam the PM system, including staff. I mean, I understand where you are coming from but I think that is why the contact page exists. Instead of trying to seperate permissions to make the 25 post count rule apply and not.
Agreed I was just stating maybe if a user was getting bullied or got any major questions, But you also stated a good point
We where all new user's though at one point of time!