Thanks for this information, with all symphaty to the victims and their families.
We can always improve products technically to prevent wrong operation or demounting. But, again, nothing can 100% protect against an operator with insufficient knowledge of the product.
For pressure retaining components, where released content can give damage to persons, environment and equipment there is a well known common known routine, often used by by top safety factories:
No visits, repair or operations to vessels (including all lines, valves and operational instruments and devices) without an exact, written documentation of what is planned to do. Plans approved by qualified people not directly doing or participating in the task. In this case a descrption would be : removing actuator by losing and removing nuts a,b,c,d (illustration), replacing by T on so on.
For this incident you have the unfortunate combination of an already ongoing leakage, nighttime, and probably a pressure to repair as qiuck as possible, resulting in lacking safety procedures. (And in addition perhaps no good written routine of whom to contact and how to handle such an incident? Report says nothing about the factory's dafety procedures status or certification level, just focusing on the valve and actuator)
Safety and qulification of procedures comes always in addition to product design and safety.