Obtaining the Mac OS ROM file requires an old Mac to run TomeViewer and extract it from the Mac OS ROM update installer. This is not readily available to everyone who would like to use Sheepshaver. Would it technically be legal to provide a patch that once applied to the compressed Mac OS ROM Update tome, would transform it into the actual ROM file?

The user already has the ROM file - the patch would not provide that - the patch would only bypass the use of the TomeViewer application, and require that the user already has the ROM by means of the Mac OS ROM Update, which is provided by Apple.