Who should get custody?

Say you have this guy friend-

He devorced 7 years ago, lives in a apartment with his fiancé of 5 years and his son [ex wifes child]. This guy and his fiance are decent people but are pretty poor. The guy and his fiance struggle to keep and find jobs because she's disabled and obese, and he's faced discrimination about his age and race. He is caring but seems kind of pushy with his son [7] who has some form of ADD so you're told. The gf is pretty much the same way. They have weird rules, like he's not allowed to come out of his room when there's guests. The son isn't allowed to go outside much because of the bullies at the complex so he sits in his room most of the time. They also dont keep their home clean. Like the plastic shower mat is completely black with mold and has been for as long as you remember. They get food stamps and even tho that's not a great situation they can still feed the son at the end of the day in their tiny apartment.

The biological mom [ex] has money and pays to have it cleaned but is abusive. She has 3 other kids from random fathers living with her and they all bully the son when he visits. The mom also bullies him too. In fact you found out by baby sitting this kid that he's afraid to shower because she likes to scare him when he bathes at her house. He also wants to shower with his clothes on? Which makes you wonder about the moms new bf who DHS has said mom needs to stay away from but doesn't or so you're told by the dad. You heard he is *interested in little kids......... This woman is well off but is sadistic. Based on everything you've heard the son say, if she's not bullying all of her kids she's helping the other 3 bully him and makes a joke out of it or insists they're just playing. Apparently making your kid paranoid is normal to her. The son doesn't even want to talk to her for the mandatory phone call she gets weekly, which unfortunately gets the dad in trouble. She goes out of her way to get dad in trouble with the court. For example she'll try to take thay phone call at 10pm, when she knows the son is asleep. This way she can say she called but he ignored it.

They have been fighting for custody of thier son for 7 years and it's still going. Who do you think should have him? There is no neither option.