I was once explained by a psy on an accident ivestigation that the memory can switch chain of events in case of psychological shock, such as witnessing an accident.
The "flames"and "explosions "or the noise of the explosion are generally what struck the memory brain and in re-collecting the events later, one would have the tendency to attribute this "shock "as the first event in the chain. This can be even collectively experienced by a group of witnesses, who saw an accident.
This is for this reason, that generally investigators do not consider eye witnesses reports as factual, and generally they are contradicted by the "hard "evidence such as FDR.
If, as you said, the NTSB diregarded the 2 eye witness accounts , that could mean that the chain of event is already well established by the FDR readings..
But all this is speculation of course...