You could argue that children attending public school are "in custody". After all, they can't just leave the school premises in the middle of day of their own will. They're subject to truant officers arresting them like paterrollers on the old plantation.
While you may have a valid point, I find that having to resort to legal obfuscation and justification in order to make a case, often leads to unexpected outcomes.
Personally, I would not bet $1 either way.
I suspect that the outcome will be a local conviction that is overturned by a higher court.
Custody refers to police custody in these cases, not school or parental or church or daycare or...custody.
As much as many want to see this cop hung, it won’t happen.