What would be the reason for them to withold information that the seat could fail in zero/zero conditions if this bolt was over-tightened, when they had admitted as such to many other organizations?
Mods/upgrades/advisories are carried out constantly as issues are found on seats, why would this issue be any different?
Lacking precise detail (because MoD omitted it in court and in all likelihood no-one knew to ask), the key is a proper contract being in place. This has not been MoD policy for over 20 years (which coincides with the reported timeframe) and, as I said in a previous post, there are well documented cases of companies giving up and refusing to work for nothing. If or when a contract was later let, the gap was never filled retrospectively, which translated into missing information in tech pubs.
Not saying this is what happened here, but it is the starting point. It is entirely possible that MB sent the information, but there was no-one in post to process it. There is still much to do, and many MoD staff involved, after the initial notification hits MoD. The various ART reports of the early-mid 90s are consistent in this area - it was not funded and much work was not done.