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I haven't researched this much further, as instances I work with all have ScriptRunner available.
What about Confluence?
There is now a Confluence version of the inactive_users SQL at https://github.com/redradishtech/jira-user-deactivator-groovy/blob/master/inactive_users_confluence.sql. Note that the SQL doesn't limit itself to Internal directories yet. I haven't made a Groovy deactivation script based around it yet.
Conclusion
Using ScriptRunner, we have implemented a means for Jira to automatically deactivate inactive users, thus saving license slots. This is (to my knowledge, as of ) the only implementation that handles never-logged-in users. Users who require more flexibility can use the SQL-augmented approach.
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