For starters, “scrubbing” is already available for use here as with any other workout:
You can easily use this to move ahead to the end of the workout whenever you want.
TR’s Workouts page will not load for me now, but I suspect if you read the description in that workout the extra part of the workout is more than just an extra long cool down. It may be a lower than normal power target, but many other TR workouts include “bonus” work like this, with the aim of adding “easy” loading to your training.
It’s akin to the cool down extension they have recommended for years, when people want longer workouts than what was prescribed. You can edit the workouts to suit your needs and time, but this is probably not just an extra long cooldown like it might appear.