We could raise participation by asking the interviewee (out of the kindness of their hearts) to post/tweet/announce the interview so their fans come and visit us. Some members of our site might actually find out about it that way, since not everyone know/reads about chat & meta.
I would add that this same issue is visible on the site chat page: http://chat.stackexchange.com/?host=blender.stackexchange.com (oddly none of the other chat pages are styled with the new blender site theme.)
This also occurs in any of the B.SE chat rooms.
For example, part of the conversation with Mike Pan today: (Don't hate on Mike, he realized his mistake soon after :P)
You can barely see the "Blender Stack Exchange" next to the new logo.
To elaborate on what gandalf3 said, no you can not just block a user from your chat room.
Chat room are set up to be public, and in normal rooms there is no mechanism to banish a user from just that room.
The "kick-mute" feature will last (depending on how frequently the user has been kicked) 1, 5, or 30 minutes. So it is not permanent.
Now you can create ...