Here's what I'm planning on implementing (this can all be server-side, and can be in a content update next week):

1) If you're the host, you're always allowed to boot.
2) If you're in a game with a valid host, only the host can boot
3) If you're in a game with no host, the boot button will initiate a 10 second vote. If at least half of the number of players that are in the game also vote to boot the player, the player will be ousted.

Thoughts?

-ALS

PS. 1.7 adds an optional minimum level requirement for the dungeon, so as the host, you can specify that an AO3 game is guaranteed that only 45-50 can join.