He sounds frustrated, autistic kids can get easily overwhelmed due to different sensitivities, planned time outs every now and then could be a good idea. See how long it takes him to get frustrated and time it before it to prevent it.
This is an idea based on typical animal behaviour, which I think is more familiar with children, however one reason why aba doesnt work is that it's not even based on animal behaviour research, and another is that it fails to take into consideration the detriment it has upon human beings by using methods that suppress growth of a human and the needs an autistic kid will have later on.
In animal training, we don't make the puppy do things, we stimulate the brain of the puppy to come up with some good behaviour and then we reward. In ABA it is forcing/faking/synthetizing behaviour, and it doesn't work because the brain never learns to actually do the behaviour itself or exercise abstination.
It is alright to read and research, if there is information, you don't have to make everything up yourself or think it out, the risks of thinking it out is that you will come up with an idea that might work theoretically but not in practice. Or work temporarily, or in a medium, but when outside it it will fail. And it's also best to consider the least detrimental methods to have in mind a healthy mental growth of the child, so you won't need to fix additional problems and so the individual can be independent as much as possible. The more information you have, the better your plans can become.
another mention is that puppies are meant to follow commands, but from a kid you will start needing them to grow their own personality, sense of right and wrong and capacity of analizing, which is bad for dogs, because they can't process human life and make the right decision at any age in their life, but is expected from children and adults, especially successful autistic ones.
