Let me explain why the implementation in XF is wrong.
It appears the reason you're not allowing this to be easily disabled after enabled is that you've triggered a timestamp so you can show a Last Updated reference. The Last Updated reference in itself is incorrect and a problem. The terms, as written by an attorney, will have a last modified date in the document itself. The Last Updated by XF is not an accurate representation of when the terms were updated, it's only a reference as to when it was enabled.
A proper implementation would first and foremost have a bit that allows a user to turn the feature to force terms or privacy on/off as desired. An expanded implementation would allow the user to enter the last updated date or whatever you want to call it and show that value. A final option would be to update a date and then force everyone to view the terms again and accept the new terms. There is no way in the system now to change terms and force everyone to view/accept them. We see this in software installers, each update has to be accepted.
The final problem with this implementation is you've driven yourself into a support problem such as so many have asked "how do I turn this off" as you've not implemented an intuitive way in the Admin CP. Instead you have to search the forum and find workarounds.
An incomplete implementation that needs to be taken to a proper implementation IMHO.