Autistic volunteer (adult man) acting inappropriately with me (supervisor)
I am the volunteer supervisor at a charity and we have a volunteer who's 40 years old, autistic, and has a very low understanding of social situations and appropriate behavior. He's very loud, obnoxious, annoying, and if you say anything he will "sorry, sorry, sorry..." x 1 million. He was onboarded as a volunteer before I started this job by my predecessor. My boss has some reasons she wants us to keep him around like it looks good in the community (small town).
The problem is, he seems to be interested in me and he doesn't understand I'm only nice to him because I'm at work doing my job, not because we're friends. A couple months ago, he texted me asking me if I had a boyfriend, telling me he wanted to meet my parents, and he called me "dear." I told him I don't answer inappropriate questions. There were also several incidents where he spammed me and so he has now been blocked. There was one incident with another young girl where he grabbed her hand in the lobby, in front of clients, and twirled her around and said "I'm gonna be your boyfriend, you're gonna be my girlfriend," etc. Yesterday he said to me as I was making a list of tasks for the volunteers to do, "are you writing me love letters?". There have been other incidents too, unrelated to inappropriate relationship comments.
I have told him before after other incidents that he is not to talk about relationships while volunteering with us. I don't think he understands.
This is my first management position, I'm 25 year old woman. His comments do make me uncomfortable and are really bothering me.
Does anyone have any advice on what to do or how to handle this situation?
My boss says if there's another serious incident that we can let him go, which I really would like to because I don't like him one bit. But I don't want to seem like I'm incapable of managing people either.
Update: I'm not against working with autistic people just because I dislike this one autistic person. We have 2 other volunteers who are autistic and I have no issues with them. They act appropriately, are respectful, and do their jobs. I have spoken to this man about his behavior and my boss has as well and we do our best to accommodate him but the inappropriate behavior and comments just don't seem to stop. That's what I'm asking for advice for - what to do next.