JJ likely rewrote everything rushed last minute under orders from Bob Iger/Kathleen Kennedy. When they fired Colin Trevorrow, it fell on JJ to pull together all his scribbled unused ideas from TFA. This is why ROS doesn’t really feel like a story and just a string of random ideas–that’s exactly what it was. It almost seems like JJ was told NOT to use anything from the Colin script.

We can reasonably guess that JJ had “–Kylo Visit Mustafar” in his idea list and just slapped it onto the wayfinder quest footage when it didn’t fit anywhere else.