2 things:
1. I have seen exact same offensive message for many times, most often it WAS used against new players who are not aware of rules, and who rage the server, calling it bad. I was informed things have changed, and such attitude have been dropped. And here you brought it up again. I and We know that we are free, such message should not be reminded in such way, makes me/us feel very unwelcome and disrespected of our presence.
First of, it's never used against anyone. These things won't change and there is no "such way" of saying this message but loud and clear. If you don't like the server, you're free to play wherever you like. This is just a reminder for all those dissatisfied. Maybe those who feel threatened should moan and rage less inside the server and actually post a thought in this board. Save themselves some time and nerves. If you feel unwelcome after this message then you're really not welcome. I was told this sentence a lot when I first arrived and it gave me more desire to participate in changing this community. Never scared me away. I advise you not to take it as a threat.