machaca
howdy. I see two planar considerations for Fin performance, lateral (side to side), and longitudinal (fore and aft). Each of these planes is addressed separately. The pins and brackets snub each stress in differing responses relative to strength. The side to side is captured by a narrow breadth of lug to lug span, the longitudinal by the distance of the saddles fore to aft. The longitudinal consideration addresses drag, the lateral, Rudder deflection and or fin divergence from airstream (Fin/AoA). The stronger structure reacts to drag (it has greater length, or 'pivot'), and the lateral relies on a shorter throw to control what I see as a potentially larger stress, that of side to side sweep, the action that destroyed 587.
Each of these planes is of course rectilinear, though the stresses are not always so in flight. The Fin and Rudder are constantly changing their respective 'attitude' depending on the slipstream, and control inputs. The failure of 587's VS started at the aftermost right lug and rotated forward capturing each of the other lugs in sequence, in a circular motion due to torsional, side to side, and longitudinal stresses. The alteration of stress puts right angle joints at a disadvantage, for the designed consideration weakens as the stress partner acts in the other plane.
An airload that could be responsible for the removal of 447's fin could be drag alone, in overspeed, with an overswept Rudder. Such drag would put a great load on the aft bracket downward into the fuselage, perhaps scrubbing the Rudders corner as it pressed down into the tail cone. If there were other stresses in 'concert' with drag, eg lateral and longitudinal, it would not surprise that the Fin may have failed sequentially, losing its joins 'gradually'. Remember that 587's engines were scraped clean in an aft and sideways manner at less than 210 knots.
Further, looking at 447's powerplant, with no vestige of pylon or wing structure attached, one's breath is taken, and to consider that somehow a rather fragile structure as the fin survived 'unscathed' simply defies logic.
Nothing of what I propose is meant to dissuade or foreclose other explanations, at all. I am astonished at the complete disintegration in the debris field here. Absolutely nothing seems to have remained attached to anything.