I don't think so.
If I were an Uvalde prosecutor (and I'm not even a lawyer so I have limited knowledge of the law) then I would charge the police on the grounds that they protected the murderer from the parents without actually doing anything to arrest or kill the murderer. The police were effectively serving as protection for the murderer. It would be legal for the police to detain the parents in the course of the police doing their duty - for example, the police could hold the parents back while other officers engaged the shooter, but if the police aren't fulfilling their duties then they have no legal reason to detain the parents and are therefore engaging in criminal acts to facilitate the murder of children.
I would take a list of the children who died and charge all of the non-responsive officers with the murder of the first child on the list under this theory. If a jury rejected it then I would charge the officers for the second child on the list, possibly with an updated theory of the crime to account for double jeopardy or to anticipate the police officers defense, and keep going until I found a sympathetic jury or ran out of victims.
If the supreme court, or any superior court, would overturn this case that would have to happen after the case was decided in the lower courts and while the officers languished in jail and I would fight to delay any overturning as long as possible.
Apart from the law, the basic facts of the matter are that nineteen children were murdered and the police are largely responsible for that fact. Of course the murderer is the one who ultimately killed the children, and bears the most culpability, but the police had ample time and opportunity to engage the murderer and save the children and did not. Morally, the police are absolutely responsible and I think a creative and aggressive prosecutor could find a way to present the fact pattern such that a jury would agree.