To be fair, it's difficult to measure IQ for nonverbal peeps. I've met my fair share who were either borderline or average intelligence. People assume kids who are nonverbal are total speds, but one should presume competence (till there's no doubt they're stupid as all hell). Nowadays, more and more are learning AAC or just outright learning to write. The best stories are when the 12 or so year old just starts writing on their own or typing. Like, ABA so shit it couldn't help them get there faster.
This is my main beef with ABA - communication should be the main focus at all costs. So many nonverbal kids learn late because ABA is not rooted in modern speech path knowledge and sucks up the money that should be going towards other shit.
I've also met at least two who have/had serious speech issues that would've been much improved by a speech path, but all they got was ABA (which is not qualified to help the kid learn to pronounce). The really sad case was the one whose dad thought he wasn't all there in the head, but by all accounts the kid was average intelligence with fairly bad speech.