They're not morons.
@ sisk:"I don't know what kind of morons have been arguing against the restrictions that would keep legitimately mentally ill people from buying guns, but they should be on the receiving end of a clue-by-four."
The problem with that was illustrated in an article* on gender crossing by the University of Chicago's Deirdre McCloskey last April:
"In most states even now, if two people who don't know you from Adam (or Eve, for that matter) are willing to claim falsely, and without penalty, that they heard you threaten to kill yourself—or in my case, threaten to have a nose job—sheriff's deputies will escort you in handcuffs to the local locked ward for three to five days of observation.
"What's worse, they might keep you there indefinitely, particularly if you let them drug you on admission. No kidding. If you are accused of murder you at least have a chance of getting free sometime, especially if you are innocent. If you are accused of being crazy, the government can put you away forever on the say-so of one psychiatrist."
McCloskey can't legally own a gun in the US. She hasn't committed any crime whatsoever, let alone a violent one. She's actually been a TARGET of state violence.
The legal picture she painted is also a bit too rosy. In Minnesota (where I live) there's no requirement for multiple witnesses. There's not even a requirement for probable cause - in other words, they can hold a person for 72 hours even if it's clear that they COULDN'T be committed under the law. There's no written standard of what it takes to justify it - just a no-string-attached delegation to the professional opinion of the person doing it, plus a broadly-worded good faith indemnity to make sure that they don't take that duty too seriously. There's not even a minimum standard for what has to be done in those 72 hours to ensure that the rationale for detention is factually accurate.
(The worst example that I can give you is a child abuse victim who was held on the say-so of their abuser despite having both an extensive Child Protection Services record on-file and cell phone photos in-hand documenting the abuse. There was nothing they could do afterward because there is no requirement that the clinic staff bother to look at any of it - even if doing so would take a mere 30 seconds or a five minute phone call to have the records sent over.)
There's also no right to a public defender, and unlike a person in the county jail, someone on a psychiatric ward is liable for a bill of $1,000-2,000 a day. That's $3,000-6,000 after 72 hours that they won't have to hire a private attorney.
So the problem with your suggestion is that the majority of the people who would be swept up in such a dragnet are abuse victims or harmlessly odd people who've spent their lives as human piñatas.