Sorry to hear about your son & his PTSD condition. I somehow suspect that by you introducing him to a meaningful pastime & trade, that he'll become absorbed in it and hopefully that just might help his situation.
Looking further, it sounds to me that this could be a new project for you. Build a new shop for your son, have him sell his product & then pay you rent to pay off the new shop. Then you'll have your original space for yourselg, or if he decides to go on his own (elsewhere) you'll have two (2) shops! Now how good is that? LOL
Thoughts entering one's mind need not exit one's mouth!
As I age my memory fades .... and that's a load off my mind!
"We Live In The Land Of The Free, Only Because Of The Brave"
“The problems we face today are there because the people who work for a living are outnumbered by those who vote for a living."
"Socialism is a philosophy of failure, the creed of ignorance, and the gospel of envy, its inherent virtue is the equal sharing of misery." Winston Churchill