Most mass shootings are overwhelimingly commited by men. More mass shootings have been commited by incels than trans persons. About half of male mass shooters have had legal problems with violent abuse of significant others. Many have a history of mental illness. Yet the NRA and like minded progun groups oppose red flag laws.
They're right to oppose red flag laws--the problem is the laws are basically guilty until proven innocent, generally with no way to prove your innocence. Make a red flag law that's fair to the falsely accused and you'll get a lot more support. The
concept is good, the implementation is not.
The trouble is that buying weapons that can be readily used to kill a decent number of people in America is so simple, that unless red flag laws are as you note, they'd be effectively useless.
But I get your point, saving the lives of a small number of people isn't worth the cost of restricting access to guns to people that might not be in the right mind to own them.
More, they want to wait until they figure out how to make a law that lets them have guns and doesn't let others.
This is why they tried the mental health angle, so that they could consider being LGBT, enjoying weed, etc as psychiatric conditions.
It's much like the drug war: if they cannot engineer it to attack people they dislike they won't try.
You can guarantee that it's going to be different in certain states. They are going to declare being trans a mental health issue and declare being a spouse beating violent shit to be "nothing to see here", same way as they use ID requirements to shop for voters based on which demographic has which type of ID.
Then, certain well-defined and well-agreed conditions could probably serve to be explicitly banned: those who have committed a violent crime involving the use of a weapon.
A weapon here would be any tool which has been modified or designed with intent explicitly to present danger of harm to some party along some dimension of it's use.
For example a gun has been designed explicitly to present danger of harm to some party along the a cone calculated from the walls of it's barrel, relative to a firing pin.
If I were to remove the firing pin of a gun and go on to commit a violent crime, ie. striking someone with the barrel, this would not be sufficient to trigger the law, as envisioned. It has been designed or modified to not explicitly present real danger of harm. The intent was clearly to intimidate and not harm, even if they happened to have a heavy object.
Let us contrast this with striking someone with a belt wrapped around a fist. This would be sufficient to trigger the law, as the fist has been modified with the belt to present an explicit danger of harm through the dimension of repeated punches, made repeatable by the presence of the belt, which enhances the hardness of the knuckles. It involves the active modification in real time. Wrapping a hand with a belt takes an effort pulling out a gun that is immediately at hand without the firing pin does not.
This is set up this way because it goes into a calculus of whether the person is one who seeks weapons for use in the commission of a violent crime. Gun crimes are exactly terrible because the person seeks out additional danger to present to folks, and this mindset IS the red flag, not the violence, but the improvement of it through active weapon-seeking measures.
This is the form of law that protects gay people, and autistic people, and black people in their right to own guns, and will take guns from wife beaters, child beaters, and people who brandish actual loaded weapons at others on the street.
Red flag laws cannot, must not be made more complicated than that, because if they are, they will be overly vague and useful against minorities.