At my school, we regularly have speakers come in and discuss various topics during ToK, mostly because the regular instructor doesn't have any idea what to say.

This sounds really easy to fix. Most instructors are used to having a curriculum handed to them in textbook form. A list of good articles (whether from Less Wrong or elsewhere) would fill that role. Read a post as homework, discuss in class, repeat. Throw in an occasional writing assignment for writing practice and grading. This would be dramatically more valuable than most high school classes, and easy to run.