The developers of MAME/MESS get to decide on the license of the MAME/MESS source because they wrote it. That source does not include any roms, because they didn

The developers of MAME/MESS get to decide on the license of the MAME/MESS source because they wrote it. That source does not include any roms, because they didn't write those. They're not asking you to open source your game because they're not proposing to open source your game. Sounds like you're angry at the wrong people.