Apple almost certainly has both the raw ROM image and the source code in their archive. Remember, in the past they’ve shared things like the original QuickDraw, MacPaint, and Lisa operating system and Office System source code.
That's a good point, though it's not like they'd be able to release stuff that they'd lost.
(What the chances are of things getting lost - who knows. Apple may well be unusually well-organised. But my bet stands. There are a lot of non-zero values.)
I know some of the people involved in those releases; Apple has been extremely diligent about keeping all of those artifacts in perpetuity. They use geologically-stable offsite storage and so on, and keep that stuff for IP protection reasons.
