I'm sure the license agreement boilerplate attached to any and all MacOS software updates includes some blather in it specifying that the included binaries are only for use by the original purchaser of the associated OS when run on original Apple-Labled hardware, blaw blaw. Thus in the eyes of Apple's lawyers it's probably at best only a shade less "unauthorized" to extract the ROM image for use with an emulator yourself than it is to just skip the middleman and download it seperately.