The days of a DA, 3w, BME or any of the other long established majors experiencing a catastropic failure are long past, ending about 7 years ago. Bearing failures, case separations, rod failures just don't happen in those engines any more so the threat of a "flight safety' or "dangerous" failure are pretty much nil. Reflecting there are risks to public saftey is a gross exaggeration. Because an engine fails to run does not make an aircraft uncontrollable. How an operator exerts control is the real safety issue.

Taking the above to another level, most flight safety issues, with a running or not running engine, is 100% related to the skill and mind set of the operator. No engine can offset poor judgement on the part of the user. Altitude and direction are generally under full control of the operator, making any safety issues one of operator inducement. Gliders don't have any engine yet they are only a safety threat when operated in an unsafe manner. Same applies to powered aircraft, engine or motor powered.

When trying to find a place to assign fault or liability, look first at the true source instead of trying to lay it elsewhere. An engine does not make an airplane crash. It only turns a plane into a glider. How the operator deals with a glider is completely up to him or her. Most RC engine manufacturers will replace or repair a defective engine but they typically don't cover damage or loss of the airframe, largely for that reason. If assigning liability was the intent of the original post, which has been massaged from the orignal text, then I have now addressed it in the manner I believe applies to the most recent stated positon.