Being a PhD Synthetic Chemist for pharmaceuticals I'm able to explain this a little better. Ethanol is commonly used for screens and such to because it is safer hazard wise. However, the reason for n-hexane is not cost as 90-95% Ethanol is very cheap compared to hexanes. It is time related. It takes significantly longer for Ethanol to dry in the air than n-hexane which is much more volatile and will dry extremely fast. Therefore, allowing for many more products to be made per day.
I use hexanes all the time and honestly it really isn't too bad having spilled on my hands sometimes, as long as it is not continual and prolonged. My guess is that these workers and the plant did not require the following:
A) respirator for the filtering the fumes (needed by OSHA and Safety standards in the US)
B) proper safety gloves (Viton) which are resistant for even immersion into hexanes
So who is to blame here, not the client, but the manufacturer. If you make anything like this in the US and they didn't follow OSHA and various safety guidelines the manufacturer would be sued, not the client. It is up to the manufacturer and the employee to demand this from the employer. The problem is that this will never happen in China because there are hundreds of others waiting for your job outside because the quality of life and pay everywhere else is so bad that you can't have a living wage without working at these places. If Apple and the other manufacters want to complain, fine, but it will only change if you move your production to a safety regulated facility in the US or Europe. That's it.
In case you needed it here is a portion of the MSDS that is on file at every chemical company in the US to follow appropriate procedures for safety in the US when using it:
Long-term exposure may cause damage to the nervous system of the extremities
(the hands, arms, legs and feet). Dangerous for the environment.
Target Organs: Central nervous system, respiratory system, eyes, skin, peripheral nervous system, testes.