Olive,
Single seat Chinny!? Whatever next?
Irrespective of the pax load and who they are, there are always the other crew members aboard a Chinny! So, apart from perhaps the implied pressure from above to get to the destination asap (itself a latent pathogen), as I say, carrying pax down the back should make no odds; you just do your best, in a crew environment, in whatever circumstances, to stay out of trouble and stay alive.
But for whatever reason, they didn't do that...... but no-one knows why for sure!
However, I can guarantee you that they didn't fly into the hill on purpose - which would have been negligent!