On the basis of what the contributor calling himself Shell Management has written, I wouldn't advise anyone interested in safety management to pay him much attention.
If we want to talk about the assurance of safety, including the construction of safety cases, let's go ahead. I keep coming back here because of contributions from others, but those contributions appear mostly (still) to be reactions to what he has said. Please let's not orient the discussion solely around his commentary, because it won't get us anywhere useful.
PBL