Seems a bit unlikely to me. Firstly the crew would have to forget to set an initial stop altitude, secondly whatever WAS in the alt window is unlikely to have been 0000. What were the previous crew doing? What does it reset to on power down?
Thirdly, isn't it usual to only engage the AP after thrust reduction? In which case it would have been a normal hand flown departure until at least 1000'
What actually happened, what the crew THINK happened, and what they'll admit to: normally 3 different things...