as set out in the article there is a 1/1000,000 O ring related failure rate for the normal design and an unknown (but now know to be ~1/50) failure rate for the NASA specified design - should corporate / military entities risk life at 1 million to one ... that seems fair to me with the understanding of the crew - but it is definitely not good engineering practice (and is likely a criminal offence) to take an unknown risk with a human crew