I've now read all of this thread, as well as reports from the survivors. Nothing changes my view that in such waters the dive op should have had a positive way of tracking its DM, and hence the group. I stick to my view that the dive was severely mismanaged.
I haven't been to Indonesia or indeed anywhere in that region, but that's beside the point. There are international standards that should be applied to tourist operations seeking international customers (and indeed as someone said, probably run by ex-pats anyway). These are the standards that a visiting diver is entitled to expect. After all, the necessary equipment is neither expensive nor difficult to carry.