Their code doesn't suddenly become GPLed. A copy or derivative of their code becomes GPLed. Their original code maintains it own original status. Yeah, if yo

Their code doesn't suddenly become GPLed. A copy or derivative of their code becomes GPLed. Their original code maintains it own original status. Yeah, if you want to avoid any copy of your code becoming GPLed, avoid GPL compatible licenses. But if you're releasing your code under a free license, I'm not sure why you would specifically not want GPLed copies floating around too.