OK OP, I’m going to try and answer your question as kindly as possible and explain a few things that might help you understand this particular situation. I have some experience in this area as I have a SEN AuDHD child and I home educate.
As pp have said, places at SEN schools are extremely difficult to get, so maybe your cousin hasn’t been able to secure a place. Or perhaps she doesn’t want to send him to a school because she doesn’t think it’s the best option for him. Home education has the same legal standing as schooled education in the UK. In fact, home education is the default and school is an opt in service. Given that your nephew is non-verbal, I’d imagine that mainstream school wouldn’t be the best place for him. Also, schools can be very difficult places for ASD children due to sensory issues like bright lights, too many people, too much noise, transitioning from one task to another can be difficult for ASD children and they can also struggle to engage with lessons that they aren’t interested in or engage socially with classmates and staff. Children can be overwhelmed in these environments, become dysregulated and have traumatic meltdowns. They can be easy targets for bullying and if they’re non-verbal, they can’t speak up about any of these things. This can be a major concern for parents of ASD kids.
Similarly, public places like supermarkets, clubs, etc can difficult to manage for ASD children for the same kinds of reasons. This makes it difficult to take them out and engage in activities. Some ASD thrive better in their own environment where they feel safe and sensory problems can be controlled better.
Home education doesn’t have to look anything like schooled education. The child doesn’t have to follow any curriculum or produce any physical work. They can, but it’s not legally required. Children can learn through completely experiential, hands on learning for example, instead of sitting down and doing worksheets, etc. It doesn’t have to follow school hours/days/terms, children don’t have to do tests or assessments. What it does have to be is full time and suitable to the child’s age, ability and aptitude. So, many parents who home educate ASD and SEN kids will follow their children’s interests in order to facilitate their learning. They will use modern tech like online apps for learning all sorts of things from English and maths to music and health and wellbeing. Some children might be very in to animals for example and the parent might use this love of animals to engage the child in their learning.
So, maybe your cousin is educating your nephew according to his abilities at this time. Education comes in many forms. Even reading to a child is education. Watching a nature documentary is education. Listening to podcasts is education. Playing with play dough is education. Colouring in is education. And so on. So, whilst you might not see the value in what they are doing, that doesn’t mean your nephew isn’t learning and developing.
You say there are no safeguarding concerns. That’s great. Home education is not a safeguarding issue. Most children are safest when they’re with their parents who love them more than anyone else and know them better than anyone else.
I think it might be useful for you to read up a little bit on ASD and SEN because it might help you understand your cousin and nephew a little better. And maybe you shouldn’t bring up these issues specifically but just be a supportive ear for your cousin who sounds like she has a lot of on her plate and is doing a great job of making sure her children are well looked after, (no safeguarding concerns).
I appreciate it can be worrying when you don’t understand the situation, the child’s needs and how education doesn’t have to be delivered through a school environment, but you say the children are safe, clean and fed and properly cared for and that’s what’s most important here. Be non-judgmental and supportive. That’s the best thing you can do for this little family.