Maybe the reason they didn't is that doing so is expensive, should have already been done by the supplier, this was for an unmanned mission (which have signific

Maybe the reason they didn't is that doing so is expensive, should have already been done by the supplier, this was for an unmanned mission (which have significantly looser safety requirements), which was insured (I assume), and costs to some extent recoverable by lawsuits. According to the DoJ article: "the replacement cost of frangible joints provided to the MDA that included SPI extrusions is approximately $15.3 million, and NASA incurred approximately $9 million in investigative and other costs to determine the impact of SPI extrusions on NASA operations." For economic reasons, some compromise needs to be reached between assurance and insurance.