Seth Rich was a child? I don’t get it.
I think that's part of how she was speaking in "code". She finds his death very suspicious and troubling. There's a difference in their ages so she speaks of him as her "child".
He’d just turned twenty-seven a week before his murder...older black women refer to many in their 20’s as ‘child’ as a term of endearment...
It’s an analogical expression used by some in reference to someone that they care about as if they were family, and usually have a good and close relationship with.
Normally the expression is between two people of similar age where they would call each “brother” or “bro” and “sister” or “sis”. The use of son/daughter/niece/nephew/child and mom/aunt/dad/uncle ( I’ve never seen dad or uncle used as the older tends to be a woman, although I suspect it has been used) usually occurs when the age difference is considerable enough to be as if they are a parent or older relative.