Many of the posts in this thread seem to me to have veered off topic and to be venting general libertarian anti-mask rhetoric rather than addressing the issue raised in the original post - which was about the non-implementation by some cabin crews of the mandated wearing of masks on flights.
Whether you agree with it or not, it is a condition of carriage, and I think a legal requirement, that passengers wear masks while flying.
There are a number of laws and regulations that I don't agree with, but I accept that in both my private and professional life I am required to abide by them. I would argue that the same goes for us all.
Civil disobedience is arguably justiified in the cases of severe injustice, such as racial segregation in the USA in the 1950s, but that doesn't justify people in general picking and choosing which laws/regulations they do or do not choose to obey.