Why didn't <PERSON> stop <PERSON>?
So in Star Wars: The Force Awakens,
<PERSON> dies, killed by his own son, <PERSON>.
But there's something that's been bugging me about that. Why didn't <PERSON> stop <PERSON> (aka <PERSON>) from killing him?
Here is the scene right after <PERSON> says that he knows what he needs to do, but he needs his Han's help, and he hands <PERSON> his lightsaber, and drops his mask on the bridge. The thing is, as you can see in the picture, he holds the lightsaber horizontally, with the live end pointing to his right (<PERSON>'s left). And <PERSON> has a hand on the weapon as well. So, practically, he would feel is <PERSON> tried to turn the saber to the side, or to point it towards <PERSON>.
Ok, I'd understand if <PERSON> had died because <PERSON> drove the 'sidebar' of his lightsaber through him. Eventhough <PERSON> had spent a lot of time around <PERSON>, and was familiar with the lightsaber, <PERSON>'s lightsaber didn't have the sidebars. <PERSON> has probably seen <PERSON>'s unique lightsaber before, but I could accept that he forgot about the sidebars. 865
This is if <PERSON> had stabbed <PERSON> with the sidebar.
But in this scene, it's pretty obvious that <PERSON> did not stab <PERSON> with the sidebar, but with the full length of the lightsaber. Which means that he must have turned it from facing his right to facing his front. And <PERSON> had his hand still on the lightsaber! So he must have felt <PERSON> turning it around to face him.
Why didn't <PERSON> stop <PERSON> killing him? If he was that much older and weaker than <PERSON> and couldn't physically stop him, why didn't he just jump out of the way?
EDIT: In another question, it was asked if <PERSON> knew <PERSON> was going to kill him. But that question addresses what was going through his mind as he confronted <PERSON> solo (pun intended). My question is asking why he did let <PERSON> kill him. It's as if he not only knew <PERSON> was going to kill him, but he wanted it. Why? 865