If the rudder was disconnected before the flight how does anyone explain that the clevis pin was found at the accident site? Rudder horn clevis pins are typically retained by a cotter pin (split pin UK). If the cotter pin was missing the crash could possibly have caused the clevis pin to fall out. The clevis pin should always be installed head up so it is not likely to fall out in positive g flight.
If a clevis pin was missing on my tailwheel aircraft it would be obvious when I pulled the aircraft out of the hangar, obvious at first attempt to taxi, and if I somehow got that far, would likely cause loss of control at start of takeoff roll.
Sorry, but there is no way this rudder was disconnected when the aircraft took off. It is also unlikely that a missing split pin contributed in any way to the flight anomaly that was being investigated.