Being "over weighted" in order to offset an irrational fear of being unable to hold a safety stop on a deep dive should throw up a ton of red flags. A good DM would intervene at this point and either convince the diver that they need no more lead than any of the other shallower dives (all things being equal and assuming she could hold a stop before) OR convince her NOT to do the dive since she was apparently nervous enough about the dive to be observable. Ideally, there should have been a very strong effort made to prevent her from doing the deep dive with (apparently) way too much lead.
Either one or the other.. get her to bail on the dive or use a reasonable amount of weight. It is unclear if the pair were ascending along the line that was connected to the wreck? If so, a diver could be very buoyant and ascend on the line using it to hold themselves down. If this were the case, the decision to chase the weight pocket was even more unreasonable.
Sounds like a lot of bad decisions. Going after the dropped weight was unwise, but is perfectly understandable. Once a person is scared, has irrational fears and inappropriate perspectives, it is so easy to fall into the trap of "chasing something" that does not need to be chased.. Like a dog chasing a ball into the path of an approaching car. She clearly was unable to prioritize things, didn't have the situation under control and was unable to implement an emergency response that was logical.
Very sad story. I'm not a big fan of some integrated weight systems.