Exactly, it would promote the server and their channel, but they would have limited permissions, maybe even standard permissions due to the fact they have not applied for staff positions or shown they are capable of dealing with the things a moderator would. Their job would be to make promotional videos to say, 50k subscribers, but it's up to the media team to set up the events and decide if they are worth recording, it's not up to the YouTuber.
They have twitter but not a media team yet, the reason for this thread with about 3 pages of support :P