L.D.
We have a neighbor whose son has "high functioning autism" and “echolalia”. He sounds exactly as you have described this other child. The Mom was so sad because he had NO friends and was always getting picked on at school. The Mom is super sweet too. My son who is 5 , didn't want to have play dates with him anymore because he was constantly pushing my son hard or snatching stuff out of his hands all the time. The Mom was actually the one to say that she would understand if my son just didn't want to play with hers anymore.
I suggested that from now on when we get together, we sit down and play with them instead of letting them just play alone. Next time they came over I got out my son's play table, play-doh and fnger paints and we all sat together each at opposites sides of the table. Next I got out the bubbles and sidewalk chalk. They were playing together, but separate with me right in the middle. It worked out so well my son actually had fun and was sorry to see him go. It has been smooth sailing ever since with me always in the middle. Now this boy feels like he has a friend =-)
Maybe that will work for you?
Best of luck!