I'd forgotten about the miners. First time I played I managed to free them (with great difficulty) before the Sentinel Island section so it wasn't quite such a mystery, though apparently that wasn't supposed to be able to happen which is why the doors now remain locked until an appropriate stage. After which I did wonder how they managed to get away.
Regarding the inhabitants of Broken Valley in general, I figured it was possible that, since "Talana" had advanced warning of Damian's fleet arriving, others may have too and made their escape, possibly including Elsa and Fanny who were presumed to be caught up in the unpleasantness; though I think it's unrealistic to assume everyone would have got away judging by the screams and Damian's self-satisfied sneer when he attacks Broken Valley village. Part of me thinks it's silly to be this bothered, but I guess a game is doing something right if I am!
I didn't even know about Michael's raft, though in my game it's still moored with Michael's body on it; although I guess your point is that he was well on the way to Orobas Fjords by then...