Jimmy, there is a difference. Axl never quit GNR. He was never fired either. So in my book, he is the only? member who has any rights to the name. Traci Guns has been gone 20 years, Adler about 15. There is absolutely no reason either one of those guys should get to use the GNR name.
you could say the old members 'quit'.
you could also say they were marginalised to the point of irrelevance, blackmailed is another word that springs to mind as well