AF
I see you are somewhat alarmed that it has been mentioned that we are dealing with hitherto potentially unknown properties of fuel. Regardless of what the AAIB and Boeing are currently investigating, you should perhaps instead think of the investigation as more of an intellectual investigation.
Not to detract from the seriousness of the incident last year, the key is that incidents such as that are now so rare, that the few accidents we do have are no longer caused by extremely obvious errors in piloting ability or build quality. It is natural that people will of course now work to reduce this risk as well, but you have to imagine this risk as miniscule in relation to all the others that have been dealt with over time in the past, and of more intellectual interest than of clear and present danger on ETOPS flights.
I try not to read too much of inference into web posts. It's useless. So. You say the Rollback on 038 is the only incident of its type? Not so. Unless you mean the only one causing an accident.
Under these circumstances, I believe that the AAIB and Boeing do not consider this event to have ever occurred at all before under these circumstances. Nor do they expect it to in the imminent future.
I understand that they think they know what caused it, that procedures have already been altered to minimise the risk, but that the exact, precise chain of events is hitherto still unknown.
We live in a modern world where everything is instant - there is a reason many of us are not research scientists, as we are not patient enough. There is however a place for the detailed and diligent work that those people are doign right now, and will be for some time on the problem that occured to the aircraft.