It's a decent Idea, and I recommend we adopt it.
I, however have a few ideas to add to the idea.
How about whenever someone on the global ban list shows up on your server, a little window pops up to all admins (of a certain level) that says "[Name|Slot] Is on the Global Ban List. Allow to Play, Remove Certain Priveleges (Auto-Denybuild Him, Turn BFF and FF of specifically for him, etc), or Kick / Ban?" the admin could then decide on whether to Allow him to play normally, to deny him certain rights, or to Kick / Ban him. If an admin is not present, he gets auto-kicked / auto-banned and the next admin to enter chooses to unban him or leave the ban.