I agree with TSB. If all passengers in an accident had editorial powers (or even commenting power) in the report it would be a nightmare and there would be all sorts of rubbish flying around. Its an expert report on a very technical matter and sorry but passengers don't usually have the expertise to keep their thoughts relevant or technically accurate.
The passengers views are taken into account in a report - following extensive interviewing of the survivor(s) by the investigators, but they have to be screened by the expert interviewer to keep the content within the bound of sanity. TSB's definition of the two groups is totally reasonable (and I suspect an ICAO standard).
What can relatives of deceased passengers possibly bring to a report, other than something they heard on "Air Crash Investigations" on the TV?
HC