Will your child run with you? Highly doubt that, he will play with the computer.
Will your child play with you? He will, but at some point he won't.
Will your child guard the house? He won't be at home, at school time, so no.
The list could grow. Also dogs are loving creatures, they love to spend time with you and wait for you to come back. Scientists proven several times, that people who own a pet is less stressed. Autistic child is dealing with autism better if they live with a pet, a pet makes you be physically active. You're welcome.