Is the point of an edit to make the story better, or to fill time? Why is hitting a pre-determined runtime a goal?
I don’t think the issue has anything to do with runtime. It’s more about not smashing straight to the Palpatine reveal. If nothing else, the Mustafar provides a little buildup and anticipation of the Palpatine reveal. In a weird way, Mustafar and Exegol are edited like they are one scene, building towards a climax.
A lot of people (including myself, so bias) have worked on keeping this portion of the movie in… so if we remove it all together… all that work we did goes into the trash.
“That is the burden of all editors.”
Sadly, I don’t think this should be a consideration in whether something gets used. The work is always appreciated, and fuels ideas and discussions that lead towards a final decision, but if it doesn’t fit, it doesn’t fit. I learned a lot from my former boss. We spent an entire shoot day getting one shot, and in the edit room he decided to cut it without hesitation. It turned out we didn’t need the shot and he was right.