Who is at fault?

My boyfriend is on a trip to the mountains with my parents and me. He has extreme executive functioning problems and it takes him 3 hours to get ready in the morning. It’s not possible for him to take less time and he has to organize all of his things or he feels extreme stress. I warned my parents he was like this. As a result he has to wake up much earlier than all of us. My parents wanted to be on the road around 6am to go into the mountains since it gets dark around 5 now so we agreed he would wake up at 3am so he would have time to get ready. He said he was fine with that but now he’s having trouble waking up. I know my parents are going to be angry when he isn’t ready to go by 6. We went to bed at 9pm. Whose fault is this?