Yeah, it's the connotation. It's based on personal opinions, which is fine. But it's rather not "literally" leftover if Axl didn't consider it that way to begin with. I don't love everything that has been out so far, but I can recognize this.
I understand that. The thing to me is that I 100% believe that he has enough recorded vocals, and that's the catch: Axl wouldn't throw away years of his own work because Slash and Duff rejoined, one thing doesn't have to do with the other. It's art after all, and it's not fair to disregard it if he can just do what he's doing: repurposing it with the current lineup.
The problem, again, is the timing. Axl takes forever to do it, he thinks he'll be forever young and able to sing. He's dealing with the band as if he could just prioritize those old work and, when he feels like, he can *start to think* about recording new vocals. Obviously, time will show that he'll regret that.