There's also a question of how to handle this - I've just had a look through the extras and -testing emulators and can't see any that obviously include any roms, so the only current fremantle example I can clearly see is vice.
The problem with this is that as vice has never been promoted into -testing from -devel, it's never hit the testing queue, so QA hasn't been done on it. As QA testing is only done at the -testing stage, technically there doesn't seem to currently be any mechanism in place for preventing proprietary content from being loaded into -devel and staying there.