Idon’t understand the back and forth here? The OP was poorly worded, but the obvious question asked (implied) was “if they can’t consent to sex, what about porn?”. As others have pointed out, the law forbids exploiting the handicapped, not forbids the handicapped.
Challenged or not, he’s breaking the law. The only question is, is he competent to stand trial?
Of course you notice none of the laws quoted had “Romeo and Juliet as Dumb and Dumber” exemption? Very few laws are written to cover every exemption. My Grade 3 teacher made this point once, when the class was talking about emergencies and the law “…but don’t ask me - what if the guy has no arms or legs, how does he call the police?” They don’t write 3,000 page laws to cover every possible scenario (unless it’s Obamacare?). The extremes are at the discretion of the police and the DA.
So a guy who’s a little slow, but still functional, better already know you don’t mess with underage girls. Whoever gives him “the talk” has to be more explicit and blunt than with a normal 12 year old. The “mental age of 12” has one significant exemption, the man (or woman) has the body and urges of a 25-year-old; they just have the mental restraint of a 12-year-old and need to be better schooled in yes-no.
(I recall a local McDonalds had a Downs guy helping out, doing some cleaner work. They had to get him out when he started hugging the girls working there. At first they were too polite to tell him no, but eventually it became too frequent and creepy.)
For the OP - Obviously, whoever made porn videos, the partner who is not retarded would simply be seriously incriminating themselves if they do it on camera. The camera crew and producer, etc., would be conspiring to commit the crime. If it involved two mentally handicapped, then presumably the one arranging it and filming it would be an accessory to a crime, even if the participants could not be charged.
To answer the question about sexting - there are several issues. Like the case TMiB mentions, is the person understanding what they are doing? Would the DA understand the person is challenged? Considering they have charged, convicted, and given the death sentence to underage children and the mentally challenged, don’t expect the DA to show a mental age of over 12 either. Ultimately, I assume there would be the judge’s evaluation of the defendant and possibly a court-ordered psychiatric evaluation to determine if they are competent to stand trial. (which goes back to the other posts - not everyone with a low IQ is incapable of functioning as an adult) I can’t think of any laws off hand against luring a mentally handicapped person into sexting, but if there is any physical contact during this, a creative DA might construe it as sexual assault of some sort.