He WAS the head of automotive during the planning, preparation, and execution of the refresh S/X. He didn't become the "Semi" guy until March( made public in March, likely happened in Feb) after he got demoted. It is HIS responsibility for the planning, preparation, and execution. Not sure why you're ignoring that.
I clearly never said he was a burden on the company and I would have been thrilled if he has stayed on to run the Semi business. I've been part of lot of large scale/large team projects and I've personally seen people in management positions be excellent leaders up until the team/project grew to a scale that overwhelmed them and they started making mistakes. If I had to guess what happened, that would be it. It says nothing about Jerome as a person and as an employee. I think he would have been an excellent leader again at a smaller part of the business such as the trucking division. But in a company like Tesla where you're putting your life, sweat, and blood into your work, it's very hard to be demoted because people get fuel off of the drive to have more impact on the business. I don't blame Jerome one bit for walking.