SEGA seems to always have been a lot more generous with this kind of thing... Much of the disassembly or decompilation projects I've seen come out of old SEGA games include all the assets with them (e.g. look up disassemblies for the Genesis games), and ROM hacks are typically distributed as full ROMs - I've basically never seen SEGA use the DMCA against any disassemblies/decompilations/ROM hacks.