Would you let your child go talk to this child

I have these neighbors who go to mu church. I see them around and their randomly started being a boy there. He just sits on the porch. I didn't pay much attention to it. He had been there a few months and I didn't see him much except for when he was outside. My 13 year old went over there and I saw her talking to him. She came back inside to finish homework and my neighbor knocked on my door saying my daughter was talking was talking to her nephew. I said yeah and she said her nephew who's 15 hasn't said anything since he came to live with them. He won't even speak to his therapist. They just communicate by notepad. He's been there like 3 months and is living with them permanently. I called my daughter to ask what he spoke to her about and she just said Harry Potter. My neighbor asked if she would mind coming to talk to him again or if he could come over here. She said sure. My husband is iffy about it because.. well boys. He's iffy about boys all around and he doesn't really like the idea. My daughter doesn't mind so I think it should be her choice.

Edit: He's living with them because his dad beat and killed his mom and then himself he was also abused