@SuperDicq @iro_miya >says it is ok to use proprietary software if someone is holding a gun to your head.
Yes, running or even writing proprietary software wouldn't be unacceptable if you would literally die otherwise at no fault of your own.

Although, if such situation was clearly foreseeable and easily avoidable and you made the choice not to avoid it, it could be argued that it would be your duty to die rather than write proprietary software.

>In the case of medicine that is often the case, you often die if don't take it
It would be better not to take proprietary medicine, but it's usually unavoidable due to all the diseases and illnesses caused by proprietary things, thus taking the proprietary medicine would be a lesser evil.