Again, for me, the timeline is the issue. His mom called him and he was staying in that night. Some think she called around midnight which would be too late for someone coming to buy something and the fire was by 6 am.Less likely, but possible scenarios might include, E nowhere near to his home (by chance or force), his phone & keys stolen and used to enter the apartment and start the fire.
Not enough funds were raised, so he put an item (bike, books?)up for sale and the 'buyer' was very bad news. speculation,