Given the debacle that has been the MAX and their falling far behind the competition in terms of development, it's fair to ask only half of the original question; "Is it too late for Boeing".
Oh please. Plenty of the believers spend their time telling others theirs' is the only "true" god and that their god's word is the only path to a righteous life - especially the American believers.
If my 87 year old mother-in-law who suffers from asthma and COPD and whose lungs function at about 40% of normal can wear a mask with on problems, so can everyone else.
Delta is an airline. Those offensive passengers are buying tickets on an airline. Their behaviour is affecting other passengers travelling on an airline. It is an aviation story.
If wearing a mask to protect your fellow humans is an affront to your sensibilities, then I really have to question who exactly raised you? Choosing a piece of fabric as the hill you choose to die on is certainly "brave". /S
The professional investigators - you know, those pesky experts who are charged with determining the actual real causes of accidents - disagree with you strongly. The very notion that a flight control system could suffer such a catastrophic misbehaviour after a single point of failure is honestly laughable in its incompetence. Those pilots and mechanics didn't certify the airplane. Boeing and the FAA did. They're carrying the can for this debacle - as it should be.