In 35 years of aircraft maintenance, I've never heard of any extended deferred defect that involves loose control component rivets. Worn rivets/holes steadily worsen and enlarged holes could even scrap the part concerned when the repair is eventually carried out.
Do allowable 'free play' limits include loose fasteners? I'd interpret free play as accumulated hinge pin or bearing wear.
Loose rivets in the control circuit may well be acceptable iaw specific maintenance manual limits but I've not come across it before.
We all live and learn (hopefully).
