First of all, well, spoilers. I think it's a perfect parallel of the scene when Vader kills Obi-Wan: Evil Jedi-turned-bad kills an important figure of his past

First of all, well, spoilers. I think it's a perfect parallel of the scene when Vader kills Obi-Wan: Evil Jedi-turned-bad kills an important figure of his past, while the untrained future Jedi can't do anything but watch how a father-like figure and source of inspiration dies. The fact that it happens while sabotaging the new new Death Star and it involves the new Vader drive the point even more.