re: suspension strut pins .... whether loose , wrong size , or retaining clips missing I cannot see them falling out in flight ..... they are carrying +20,000 lbs and you could not drive them out with a sledge hammer.
On the ground with just enough lift to equal the MRG and rotor system (no weight on the pin) it could move a bit .... maybe that is what happened .... pin slid partway and only 2 of the 3 eyelets were carrying the load and bracket bent and distorted in flight .... just thinking out loud at possible scenarios.