I do not recall ever seeing a thread closed on Airline forums with Mods without the respective Moderator doing so giving a short reason.
(The one occasional non-airline exception being MilesBuzz where threads very clearly in the wrong place are moved without comment and the new forum is indicated by a UBB line. Miles Buzz being a 'catch-all' forum has this problem more than airline specific Forums.)
I seldom visit the AA forum writetorich, so did not see the thread you reference or your original (moderator deleted) post in the thread you link to above. However I am surprised there appears on the surface of reading this, to be a definite reluctance among AA Mods to concede on the board who specifically closed threads, and personally do not feel that is a wise or helpful policy.
The four Delta Moderators allowed a 4 page thread to exist recently titled: "And the Moderator's Keep on Moderating!"
No-one disputes the rights of Moderators to act in accordance with Randy's guidelines and wishes, but I do think that having acted, the person concerned needs to accept visible responsibility for that action. I would ask exactly the same question if that occurred to me in say the UA forum.