The reason that it appears as if a user has auto-pruned a forum is that the auto-prune is, as it says - automatic. The actual script that does the work is triggered when any page is visited, by anybody, and it is time for the script to run. An auto-prune can even be triggered by a guest user and it is the user that triggers the script whose details are written into the log.
Remember: You only know what you know and - you don't know what you don't know!
My CDB Contributions | How to install an extension
I will not be accepting translations for any of my extensions in Github - please post any translations in the appropriate topic.
No support requests via PM or email as they will be ignored