There is no excuse..and fatigue is not a valid excuse..
Disagree completely, it totally depends on the strength of your will to stand up and say you are too tired to do something. One's willingness to do that depends on lots of things; quality of management/leadership above you, importance of the task, awareness of tiredness.
I remember standing alone on a pan with the sun coming up taking in the fact that one of my techies had just written off a refuelling rig and seriously damaged a civvie airliner. Circumstances (op tempo, manning levels, working hours and importance of task) were such that it was dealt with, he never heard a thing about it and neither should he.
We don't know the circumstances so let the subsequent investigation decide if there is culpability.