I agree with you, but addressing the mental health issue involves many actions that are "infringing" on a persons rights.
When someone is a criminal or a danger, you go through a process to infringe on THAT person's "rights". You lock them up or institute restrictions on THEM.
You don't restrict everyone else.
And the problem with so-called "red flag laws" is the lack of due process, the lack of any evidence to 'convict', the presumption of guilt before innocence and the lack of appropriate legal redress of grievances. And most especially the lack of consequence to the state or to individuals whom use these statutes as a tool in a personal vendetta.
You don't throw out due process for the sake of expediency. It's unconstitutional. Period.