Issue for discussion here: https://github.com/jenkinsci/jenkins/commit/2be878b97cd019f61958352bd7e0cb40f6dabb40
Stop recording and displaying this information in core. Deprecate the userId field, getter, and setter. Extend slaves' index.jelly to support actions' summary.jelly if necessary, as well as any other necessary changes to support moving this functionality to a plugin.
Write this new plugin that can import existing slaves' creator information, and records and displays ownership for any new slaves. This would be compatible (as it wouldn't lose existing data, just make it more difficult to find), but would effectively remove this weirdness from core.