I agree with your comments.
I am curious as to what altitude the plane was when/if the missile detonated.
100’, 500’ 5000’? How long after take off etc.
Might help determine the type of missile, if there was one.
As to the AC having a transponder, unless someone had the equipment to receive that information, at any distance, there would be no way to know if it was military or civilian.
And I wouldn’t expect the average RPG carrying goat herder to know the difference.
reportedly it had made it to roughly 7000’ ASL. No sure altitude above ground.
RADAR guided makes sense.