11.5.10.2 - Final Closed POs

We have a hard rule that buyers should never final close a PO.  We have one buyer who has 3 that are finally closed and he swears he did not do it.  The last update on these were by him.  And the action history shows he finally closed them.  But he swears he did not. Giving him the benefit of the doubt, is there a setting that could control this and place a completed or cancelled PO in a status of Finally Closed?