Weathervaning is not the issue, the issue is the height of the crane which, correct me if I'm wrong, which was notamed and also the top of it lit at night. To me the height of the jib should be notamed as the true height and lit from the top of the jib if it is to remain extended.
Regarding whether or not the crane driver slept in or not is irreverent as he/she would probably not have gone up to the cab due weather. I can see falling to sleep whilst being on duty a factor but not being late for work. Rgds.