I think this one's going to come out entirely different from what some people think. In talking to a firefighter from the area familiar with what happened that day, here are some things besides the "jake brake" that may be determining factors...
1) In leaving their station in Moreno Valley on a cover assignment to Beaumont, it was not raining at that time. Just prior to the accident, the crew entered a downpour with limited visibility. The words to descibe it were "like parting a curtain and entering a waterfall".
2) The crew was in a nonenclosed backup engine. The firefighter who died was in the jumpseat (not sure if behind the Engineer or Captain).
I'm sure things will shake out. Unfortunately, I feel this is a result of 1) out litigous society and 2) our society's willingness to play up the victim role. People feel there has to be some way to make them feel better, but is this it?
I'm sorry folks, but sometimes no matter what you do, crap happens. It's a shame when it does, but the result is still the same.