I have not read the Rib Int mag so can't comment on the article.
But I think I know the incident involved in the MAIB case No.25 and the pictures tie up.
The comment about the safety boat needing a prop guard is interesting as the sailing site that its from fit the half guard, basically a ring not a full guard.
The story goes the leg went between the ring and the prop and caused the damage, where as a full one would have resulted in full protection and no guard would have caused laceration but pushed the leg away.
The lad is back sailing now and is rather good !