The "stupid f*cking approach" the prolific poster Mungus is referencing is a description within an earlier post that offers one approach to a 'strict liability' discipline for responsible gun ownership.
Strict Liability means.....if one is the 'owner of record' of a firearm you will benefit by the protections or enjoyment it may bring. But too, with those benefits comes responsibility. The responsibility to ensure that that high-lethality tool does not allow other individuals to cause harm with it. In short, if you own the benefits, you also own the harms. Period.
I believe the poster Mungus is referencing his own hypothetical of some gun owner leaving his gun laying on his car seat.....and when it is stolen, and perhaps causes harm, then the harm is solely the fault of the thief.
'Strict Liability' offers another approach. Meaning, if that thief shoots his girlfriend he is primarily responsible for her death, but the OOR also has a share of liability.
How much? That can be determined by future statutes or judicial decisions. And various factors can be used to mitigate and calibrate the level of liability the OOR will bear.
But underlying the Strict Liability concept is that the OOR chooses to introduced into his community a tool possessing a high-lethality potential, ease of use, easy to hide, and highly portable. And thus, by its nature it creates a risk of great harm. The OOR knows this when he possesses it.
He knows. He accepts it's risk. And thus is liable for a share of the harm it facilitates.