It would be nice to have a task set to auto complete to have the ability to have an approval process on it. We have a need for a sponsor to make an approval decision on whether or not to host an event for a project but no action is needed by PM nor the sponsor. We just need to know if there will be one. If the task is approved, then a second approval step would go to the PM as a notification that the event is approved and to continue on.
Right now, if you have a task set to auto complete you cannot set up an approval on it.