No, "they" shouldn't.

When stuff like this happens, it's a process issue, not an issue with a particular engineer. It's human nature to try to assign blame to people and that's why it's so important to avoid that. Whatever process created the flawed product is where the blame lies.

Somewhere in the group that produced MCAS, there's a process to permit changes to be submitted, reviewed, accepted or rejected, implemented and tested along with the documentation produced at each stage.

Maybe that process is broken, maybe it isn't. From the outside we can't tell. However, as responsible professional software developers what we should do is understand that these are system problems and not just look around for someone to pin the blame on.