The engineers aren't in charge.
Doesn't matter. The engineers are responsible for their own actions. They chose to commit a crime when asked and they are just as responsible as anyone else involved. If your management comes to you and asks you to commit a crime and you do anything other that say "no" then you are a criminal yourself. This is not complicated.
There's like an entire corporate machine in place to ensure that a lone wolf can't through error or malice can't cause problems. Things like basic software development practices should ensure that bad/stupid things don't go unnoticed.
This wasn't unnoticed. This was done intentionally and there were many people involved including more than a few engineers. We know the engineers knew about it because it apparently was a group of senior engineers who ultimately spilled the beans. If they knew and they said nothing then they are complicit in a crime and should see appropriate punishment in a court of law.