It seems pretty clear that the workers think that their working conditions are unjust. Further, they apparently would be OK with those conditions if they got more money.
That suggests they don't consider them inhumane, (not justified regardless of pay) rather they are economically unjust.
The truth of whether or not they are economically unjust (in a market driven economy, which China isn't really) is that if they quit there will be no one else to fill those roles (economic scarcity created by a price imbalance). However if there are people who will fill those roles at the prices offered, then they will simply be out of a job.
It is always true in market controlled transactions that the buyer thinks they are paying too much for a good and the seller thinks they are paying too little. It's the fulcrum that creates the equilibrium point for the price of a good or service.
So in a dispassionate economic way one can say the employees are working to maximize their own economic value. If by periodically pulling stunts like this gets them more pay then they are doing their part to improve their economic station at the expense of the company. The company of course may try to use that to increase the price they charge to assemble such devices, and perhaps give some of that increase to their working staff.
Saying that their other option is to 'starve' seems improbable in a country that is based on the communist teachings of Mao and Marx. One might presume (but I don't know since I don't live there) that there are state jobs available. I could certainly understand it if those state jobs were less desirable. But what I do know is that nothing, and I really do mean nothing, is the same regarding working in China as it is in any western (non-communist / non-totalitarian) country. The best one can hope for looking in from the outside are shadows of those things that are creating them.