It's a medical device that requires a prescription. You can't buy it off the shelf. They're not distributing software to you either. You must go through a medical equipment supplier who transfers the device to you after insurance has paid for some or all of it.
For the same reason you can't find an airplane entertainment system in the trash and call up the company and demand source code.
It doesn't matter what form it takes. Compiled binaries of GPL code are being distributed. The recipients of that binary are entitled to the source of the GPL portions in a usable form:
The GPL here doesn't extend beyond the kernel boundary. Userland is isolated unless they have GPL code linked in there as well. If they were careless about the linkage boundaries then that's on them.