You have answered your own question. 

The tenant will cost the school money by using an empty room, because they would need to be supervised. 

Secondly, by assigning resources to an activity, the school must explain why it is not assigning resources to other requests, and cannot selectively endorse some requests and not others, when it has determined to expand the scope of its mandate.

Therefore, the wise choice is to narrowly interpret its mandate and focus on delivering outstanding services within that mandate.