I just hope UBL wasn’t too confused to know exactly who was taking him down. He must have felt really secure and comfortable there to have that little protection.
re: He must have felt really secure
My guess would be he had been assured by the Pakistani government that they would know if anyone had discovered his hideaway and they would warn him to get out before those who were looking for him could get there. He probably had no idea what was going on and who was confronting him. I expect it was pretty dark and IMHO all armed men look the same in dim light!
Kudos to the person who decided not to inform the authorities what was afoot. That’s how he got away last time!