Using sign language requires certain skills which are often lacking in children with autism and need to be taught in isolation at first such as imitation, eye-hand coordination, and fine motor skills.
Often times, we see some basic signs taught to the child such as stop, wait, more, eat, cookie, etc. These can be extremely beneficial and helpful to the child but are limited and most of times are not expanded to a full language.
Other issues with choosing sign language as the main communication method for non-verbal autism has to do with the characteristics of autism itself as sign language is a sophisticated method and does require a certain level of executive functioning. The child has to know that signing is not visible in the dark and it does require an audience. I have often find my child pointing or signing while he is in his room and I am somewhere else in the house. Perspective taking and theory of mind play a role of how sign language can be effective.
Finally, the general population does not know sign language and is better to consider a more universal method of communication such as speech devices and typing which have their own limitations as well but are more promising and have unlimited potential.
M.Ed. Special Education/ Autism Intervention