Here’s one hypothetical example I can think of that would make me very hesitant to call in even anonymously, although I feel I would call 911 still, others may not:
I’m at the chevron with my children and make eye contact with IY inside the store. He sees my kids. I witness him force Aniah into the car and I also see other people with IY helping him. So this group of thugs knows what I look like, has seen my children and knows my car (possible took note of my liscense plate, who knows). Sure IY is in custody now but not those accomplices.