I'll say two things:
1. I don't believe there is a universal red flag law. So, your post may not be accurate in every state already having a red flag law.
2. My main point here is that red flag laws do nothing about this already deemed mentally unstable person you talk about. We wouldn't have to take their guns away at all if this already deemed mentally unstable person were under lock and key while getting the help they need. But, we take their guns away and let them roam around free being a danger to society. It allows them to either get guns using a different method or to use another weapon of choice. I'm saying that red flag laws don't actually stop anything if we let this already deemed mentally unstable person just run around loose. I'm not trying to frame this thread as anything to do with the second amendment. I'm asking the left why we find someone to be a danger to society, take their guns away, and then just let this person who is a danger to society just run around loose.