Nope, I assure you that none of these passengers were told that there was a chance that they could be burned to death and also did not consider the possibility of this at all. The fact is that they might have been told that there was a smoke detector (that never went off by the way). Do you really believe that an Apple engineer took his entire family scuba diving and was focused on the boat burning? Didn't happen, what these people did focus on was being safe under water, period
You are always responsible for your own safety.
Looking at the pictures of the sleeping quarters it looked to be very crowded with limited access. They took that risk.
A smoke detector is a good safety device but sometimes they fail. All technology is liable to fail. No guarantees on anything in life like that.
Getting into a confined boat with a lot of other people is by itself is risky. They chose to do it.
We all make decisions in our lives. We can't always blame our bad decisions on somebody else.
The families will get money out of the settlement with the insurance company to the limit of the liability and maybe the owner has some other wealth they can tap. I am sure a jury will find him negligent.
However, I bet I wouldn't ever make it to the jury because I believe in personal responsibility.