Yeah Garp and Roger never killed any of his crew, I doubt Xebec is truly dead. But I also don't see what exactly his role would be. Having gathered a crew of rascals like that did he expect that he was gonna get betrayed and therefore planned some 5D chess move and lay low but for what, what did he do behind the scenes, did he find anything in god valley? Is there a failed clone of him? Did he get stoned or frozen by the users of those powers at that time and is only waiting for the curse to be undone? Ope ope no mi immortality surgery on him?