Hi @Matthew_Drury. Welcome. Have a look at the Asana guide specifics around Rules: Using Rules in Asana | Product Guide • Asana Product Guide
When you deprovision someone who has Rules, their Rule will be paused and ownership of any Rules on projects will be passed to the Project Owner. If there is no Project Owner, ownership will be passed to the Admin who deprovisioned the user.
There is also an product request where you can vote on allowing other users to edit rules: Allow other users to edit an automation rule.
Hope this helps!