[DonbunEf7]

This is because the one-liner is actually (sorry SSC) a valid logical template, relying on assumptions about rule of law to draw a deductive inference. We can see the template itself:

    "When X is illegal to possess under some jurisdiction's law, then the residents of that jurisdiction will be criminalized by their possession of X, and thus the only possessors of X in the jurisdiction will be criminals."

SSC probably doesn't like this one because it's definitional. People like to use "criminal" is a qualitative label for people who they feel have broken the law, but it is in fact definable as a quantitative label for people who have committed acts which are unacceptable as a fact of law.

[mannykannot]

We don't have to guess why Alexander disapproves the one-liner, as, after presenting the more thoughtful version, he writes:

"The original is a gotcha exactly because it doesn’t invite this level of analysis or even seem aware that it’s possible. It’s not saying “calculate the value of these parameters, because I think they work out in a way where this is a pretty strong argument against controlling guns”. It’s saying “gotcha!”."