The words spoken at the inquest are public, and can be freely twittered by the press, but there might be submitted material that could add substantially to the coroner's insight that is not mentioned. A fuller picture of the purpose of a line of questioning, especially live, may require an awareness of the material that the coroner has reviewed before questioning the witnesses.
It's also possible that an expert in the material could more quickly piece together more insight into the events here than the coroner, who is an expert at running inquests but not likely familiar with the engineering details.