I don't know why you assumed he need to move the rear sight to the right
You are correct that with the given information or lack of it, I had to interpret what is going on. I assumed that this was based on a group of shots, he had good form and cheek-weld and has some experience, after all, he is building a kit. Let's just say that I gave him credit for what he was doing. Also wanted to make sure he was starting out with a reasonable load to remove that factor. ....
Going to have to watch your future postings as well. ....
Be Safe !!!