> Quitting doesn't save Apple
Well, it kind of does. Right now we're approaching Poe's law with the use of AWA to compel the writing of code, but we're still just barely in the realm of keep-a-straight-face-defensible (largely because the bulk of the population is less tech literate than is ideal). If even a few of Apple's key security engineers quit at the same time, then it becomes very easy for Apple to make the case that they literally cannot do what is asked anytime soon (how long for a new team to cold boot with a new codebase whose domain is cryptography and no one around to provide guidance/tribal knowledge?). In any sane universe this would show that the request has crossed the line into overly burdensome. It is very hard to justify massive penalties to incentivize compliance with something that Apple may or may not be able to do anytime soon [0].
So that would basically leave them the option of stopping the insanity or going after the individual engineers and compelling them, which opens up a whole other heap of lunacy which might have to get resolved before Apple would again be on the hook for action.
If the court then decides that it will compel the individual engineers who are now no longer Apple employees to work.... They're forcing labor from unwilling non-criminal citizens (13th?); they're compelling code, which is speech, and compelling association between the engineers and Apple who would presumably need to be compelled to rehire them because you can't make someone work for free (double 1st); as someone has mentioned they could institute a draft (??) but I'm sure there would be legal contest regarding conscripting specific individuals against their will and this would require the cooperation of congress, the military, the NSA, and it still wouldn't get them the thing they actually want which is precedent.
[0] From wikipedia: "the [fined] party is said to "hold the keys" to his or her own cell" which justifies the lack of a trial for civil contempt fines. If you cannot comply, you lack the ability to escape the fines, you are not receiving due process. I think this little corner of the law might actually be the bulwark that makes zero knowledge systems legally safe as well, though if you have an auto-update system you still would need the code-is-speech, cannot-compel-speech protections to round this out.