Is there anything wrong with a seller not performing the needed due diligence to make that sale legally to keep our firearms out of the hands of the criminals we don't want to get them. Of course there is.
I must take issue with this, because to my view it relies on a false premise, at least in my state and those surrounding it.
Unless and until there is an affirmative duty under the law to positively identify a buyer and for the seller to be completely satisfied that the buyer is not a prohibited person, there is no requirement for "due diligence," and it is completely legal, and therefore, in our society governed by law, it is by definition also morally and ethically acceptable to make the sale.
The whole theme of the NBC story was to bemoan and lament the lack of a background check requirement in face-to-face sales between private sellers in some states, and to impose the "due diligence" requirement on all sellers. I reject any and all attempts to insinuate that a seller has ANY moral, ethical or legal obligation to do any more "due diligence" than what is presently required by law, which is why I take issue with the statement above.
Of course, sellers are free to refuse to complete any transaction they don't want to, and for whatever reason they want to, but it is their choice in our free society. If they choose to ignore things that would ordinarily set off a reasonable person's Spidey Sense, they do so at their peril, but in a free society that is their right.
As I see it, any talk of "due diligence" outside a legal requirement to do any is capitulation to the anti-gun crowd, and an alignment, if not endorsement, of their gun control agenda through incremental steps.