Sid is a guy who has managed to stay over with fans due mostly to the fact he doesn't stay around for long periods of time, due mostly to his summer softball hobby/job? He has a bit of a reputation backstage(from being difficult to the scissor fight with Arn Anderson) and the fact he is out for a really long time with that leg injury makes him a non-factor to the WWF/WCW. And why would Vince feel the need to bring him back due to the injury, it didn't happen on his watch.