Should we appeal SSDI/SSI denials?

My 35 year old son was denied for both SSDI and SSI recently. They reached a conclusion bery quickly and stated that they did not need any further information and that he should be able to do work that is not stressful. He has struggled all his life with social anxiety and depression. He has been diagnosed with ADD, PTSD, and most recently, in 2017, with Aspergers or HFA. The denial recognized the depression and anxiety but there was no mention of autism. He has a letter from the psychiatrists office with that diagnosis. The other part of the concern is his work history. He has had a couple of jobs that lasted over a year. Most recently he has been pursuing self-employment but without profit. His last paycheck was summer of 2017. We don't want to waste the time and energy if it is a forgone conclusion that he does not fit the requirements, but our time for appeal ends this week. A professional opinion would be helpful. Thank you for your time.