Okay, but put on the other shoes for a moment. You get a call from your favorite cousin who needs you to help hide their kid who has just killed someone. The first few days, okay, they might not have heard about the case, but this far in, there is no way anybody helping him doesn't know he's wanted for the murder of Gabby Petito. It's a crime in every state to harbor a fugitive, you're looking at five years in prison if he is charged. Not convicted, charged.
Do you harbor the fugitive? Do you risk having your entire life destroyed for a nephew? Most people aren't going to do it. Or do you get that sweet, sweet reward money? I love my nephews, but I'm not going to jail for them.
Where ever he's hiding, they don't know who he is.