How are you going to do that?
Sending police to pound on the door and demand they give over their guns is ensured to end up with someone dead.
There is likely no higher probability of death than to send police to attack someone who some one else claims is "clearly deranged".
There is no way to use "Red Flag" sanctions fairly because the person never gets to defend themselves in court.
So it is totally one sided, possibly lies, and totally illegal.
If someone thinks someone else is a danger, you most certainly DO want to lock them up, do a full mental evaluation, and find out if they need treatment or to be locked up permanently. For anyone too dangerous to have a gun is too dangerous to be allowed to drive, have gasoline, buy toxins like pesticides, etc. And taking the person's legal guns is not going to stop them from just going out any buying illegal guns from some drug dealer. Every drug dealer has to be armed, so they always also have arms for sale without any trail.