I feel like a lot of people don't understand the electively home educating option that it sounds like the woman in question has taken, which for many parents of autistic children, is not all that elective when you're faced with a punitive and time consuming EHCP system and a mentally taxing and traumatic schooling system.
It's usually a necessary step in keeping out children's mental health stable, and reducing school based trauma.
You don't have to do a home education programme to be a home educator.
You don't have to do the national curriculum, you don't have to join homeschooling groups, you don't have to aim for any qualifications or have your kids sit any tests, and the education does not need to be based in academics and it doesn't need to fit the 9-3 model.
It can be life skills, emotional regulation, independent living, or simply allowing space for wellbeing and recovery.
You can raise a safeguarding concern if you feel that the education the children are receiving is not matching with the child's age, aptitude, or medical needs.
Ultimately she could argue she is teaching them independent living and life skills by allowing them to live a fairly independent life at home. It doesn't matter what time they go to bed or what time they wake up.
Video games aside, sleep can be extremely difficult for autistic people anyway. It isn't uncommon to have some sort of insomnia, and teens need more sleep than adults.
I have almost had to withdraw my child from mainstream education purely because he has delayed sleep phase syndrome and it's a long wait to get a referral for paediatric sleep consultations. I wouldn't be able to get my child to engage in the national curriculum at home.
Video games can teach skills like fine motor coordination, team building and cooperation, creativity, emotional regulation, reading and problem solving.
They can also be immensely validating and part of the dopaminergic reward loop and offer predictability and control. They're a good way of socialising with all manner of people.
It can also teach IT skills, finding ways around systems, installing and troubleshooting when things like custom mods are involved, programming and decision making.
It can teach engineering skills to children who are interested in building their own set ups, and they can learn about systems which many hard-core gamers do as it is an investment in their hobbies.
Her teens may not be in a place to learn right now but they might be in a place of curiosity and self regulation.
But as I've said before OP if you truly believe they're being neglected, then report them to the police today who will have a social services worker on hand that they can escalate safeguarding concerns to.
I do know of one girl who was hidden away from society and hardly any one knew she existed, and she was the daughter of the old man who lives over the road from me. She was very high needs, diagnosed with infantile schizophrenia, and even when she died the body removal was organised in a way to ensure that none of the neighbours would know she even existed. A truly traumatic case of neglect that I wouldn't wish on any children, so please report it if you believe they are being ill cared for.