We don’t know that they knew he couldn’t swim.
Yes, they did know that he could not swim.
“We don’t know the real timeline.”
He was in the water for about twenty minutes and under water for five to ten minutes.
“Did his friends just sit on the dock for 10 minutes or did they call for help and the others searched, found and rescued him after 10 minutes?”
We know that his friends did nothing for about twenty minutes. He was rescued by someone coming out of a restaurant.
“You don’t come back from “brain dead” and 10 minutes without O2 should be fatal, though very cold water can mitigate this.”
Have seen only one paper that said he was brain dead. He certainly had brain damage initially.
As I said, I never make a judgement on one story.