For instance when operator ask to delete a user that does not exist.

In this situation the task should display the ipa message and return 0 to be understand by bolt as not failed. If the task is to ensure that user foo is not present, then it looks already done when the user foo does not exist yet.

Extracted from man ipa:

EXIT STATUS
       0 if the command was successful
       1 if an error occurred
       2 if an entry is not found