Do we really need the bad analogy at all?

No.

But if someone uses one, it can make sense to illustrate that it doesn't apply as cleanly as they think.

I dunno, I think a significant amount of fault lies with the developers who were either too stupid and too bad at software to create a tool that couldn’t create CSAM, or were too vile to enable the restriction.

I also think people who defend that kind of software are in dire need of significant introspection.