I’ve never been a fan of how Luke lifted the lightsaber- but only for an instant. And Ben just happens to make up and happens to misinterpret the situation.
I completely see it’s logic: it totally could happen irl. It is the best way to write Ben’s turn, as you want Luke to be guilty but still a hero. But the entire thing feels so contrived.
I honestly don’t know any other way to write that scene besides having Ben’s turn not take place in his bedroom, but some other place with other variables. I am just saying what I feel from the whole explanation.