The more they fight for OS 4.0 in this action, the more they expose the facts of the entire IP transfer. From the lack of paperwork submitted and then "redacted" other documents in general I doubt Amiga, Inc. will be as gungho as you think.
I agree with you that Amiga Inc has serious issues with their case. Maybe they can close some of the gaps in time for the trial, maybe not. And maybe the defeat of the injunction will drive them to an out-of-court agreement with Hyperion. But If Hyperion isn't interested in a deal and instead lays claim to the OS, I don't see Amiga Inc having any other option except an all or nothing court battle. Do you think they might say "Ok, never mind. You can keep the OS." ? I'm sure it's not their fisrt choice, but if pushed into it, their option is to fight it out, win or lose.