I guarantee job offers and a gofundme legal defense would be offered to any dissenting employees insanely quickly on this issue.
If Tim Cook was really upset he could start a new company called "Screw the FBI LLC" which coincidentally hired employees after they got fired from Apple...
You do realize Tim Cook is the CEO aka the one who is ultimately doing the firing in this scenario right? The US Government are not majority stakeholders in Apple.
In the UK there is this concept of a "shadow director", which is someone who, while not officially a director of the company, actually has executive power indirectly in some way. The legal concept exists to point out that a shadow director can be held legally accountable in the same way a director can.
Perhaps a similar concept applies here. If the FBI can compel action from Apple it is basically a shadow CEO of Apple.
If Tim Cook was really upset he could start a new company called "Screw the FBI LLC" which coincidentally hired employees after they got fired from Apple...