So I am to wake up at 2am every morning and manually remove a user from the security roles and re-add them at 5am when everything is done? Doesn't sound like a very modern solution...

Unprocessing is a possibility however limiting this while the cubes are being utilized seems prohibitive.

For the interim I have issued a script that will limit the memory of the cubes down to 1GB of memory during load times that do not pertain to the cubes, and then upping that when the cubes are loading. So far this seems useful, but I am having a hard time believing there is no intuitive way to locking the Cubes out from consumers when you can do that to every other single aspect of SQL Server.