system
Given the following post, respond as if you're commenting on Reddit:
human
[Star Wars] What incentive was there for Palpatine to rescue Vader from Mustafar?

The dude's won. Jedi are only a handful and all but extinct, he's the Emperor and he's got the Galaxy right where he wants. Why did he have to fly over to Mustafar like some concerned father figure if Vader couldn't be of much use anymore?

I mean, yeah in hindsight Vader was still VERY useful, but IN that moment, what made Palpatine think "hey, well...there's goes my prized pupil of the dark side, this guy is worse off than Dooku and Maul at this point. i could train a new apprentice....eh fuck it, lets go get Vader..."  why? I don't believe Sidious even cared for Anakin. There were better suited alternatives. Anakin just got beat, why invest in him again? Dumb move to make as a Sith master.
gpt
Because he was more powerful than Dooku, Maul, etc, but not powerful enough to be a threat to him any more; there were still Jedi out there, so having Vader as an enforcer/troubleshooter was useful. Plus, it allowed him to play at being the weak, frail old man who could manipulate his enemies behind the scenes.