General :: Create A Sandbox For A "half GPL" Kernel Module?

There is a kernel module that connects a SCSI like hard disk to Linux computers, as well as windows and MAC. Some portions of the source code have a GPL license on them, but some remain property of the hardware inventor. The inventor does not agree to GPL the entire code, even just the Linux code. Consequently, the connection package falls behind, the existing users feel left out and the new opportunities fall by the wayside.

The confusing thing for me is that the company gives away the end product, (the compiled module and it's editable source code) but they won't let non-employees edit the official source to keep it up to date. Ultimately they only make money on the SCSI-like connection hardware. Several users have modified the existing package to keep it up with some distributions, but there are others that should be explored and new architectures to employ it.

1) Could I set up a sandbox that hides the non-gpl source code pages, but allows willing developers to join and modify the gpl sections and then compile the modules on different architectures?

2) I have trouble understanding the difference between working on this kind of kernel package for free and releasing the code. In other words, since the company gives away the end product, just as GPL developers do, why not just agree to the same requirements you would have if hired at the company, but do the development for free in the spare time anyway?