I always struggle with these posts. I feel like, often on these forums, I see posts about people wanting other people to date them, and blaming PTSD when that person states they do not want to be in a relationship with the poster.
I'm projecting a bit, because I've been the one with PTSD saying that I want to be single, and having the other party tell me that I don't really want that, because I'm just mentally ill. Turns out, I really just did want to be single. It had nothing to do with PTSD and everything to do with my own personal place in life, with my priorities, with my freedom. It isn't always about PTSD.
He says this. I would accept it at face value. He wants to be single. Plain and simple. That means not in a relationship with you - PTSD or not. It is possible, and it sounds rather probably, that he just wants to be single, and there is nothing you can do except accept his choice.
We are offering you advice. It seems the consensus is to run.