FWIW, I fully agree with your interpretation of RMS's argument here(to be fair, I think his argument as presented was worse, but giving him the benefit of the doubt, I arrive at your interpretation). However, I don't see how that argument can be "beyond the pale of responsible discourse". This is a legit legal defense!

From what I can see, it would be an admissable defense in the Virgin Islands(strict liability for only under 13), and irrelevent in Massachusets(age of consent > 16), etc. But I don't mean to wade too deply in the legal correctness - it's quite possible I'm wrong(not a lawyer), my point simply being that I can't see how this argument is out of line, given the controversial[1] nature of strict liability, and the differing statutes from state to state and country to country.

[1] - Here's a quote demonstrating its controversial status:

> The Supreme Court proclaimed that "[t]he contention that an injury can amount to a crime only when inflicted by [mens rea] is no provincial or transient notion. It is ... universal and persistent in mature systems of law ...." Morissette v. United States, 342 U.S. 246, 250, 72 S. Ct. 240, 96 L. Ed. 288 (1952). See also United States v. United States Gypsum Co., 438 U.S. 422, 98 S. Ct. 2864, 57 L. Ed. 2d 854 (1978) (offenses that do not contain a mens rea element have a "generally disfavored status").

(Taken from https://www.courtlistener.com/opinion/2336454/francis-v-gove...)