I would think that this situation in some ways resembles the issues faced by children with younger siblings. Should they always have to include them in their games? I don't think so.
If other children understand that a child has special needs, they may be encouraged to sometimes include this child. To always have to do so puts an unfair burden on these children.
Parents of children with special needs may have to seek out other children with similar problems as playmates for their children, if their children are not accepted by non-disabled peers. Perhaps these children can be helped to develop hobbies or interests that will attract other children, or can be helped to develop behaviors that will be more acceptable to a non-disabled peer group.
What I do think is important for parents to communicate to their children is that teasing of children with disabilities is not to be tolerated, except within the context of real friendship, which often does include some teasing.
I also believe that parents can help their children to find ways of including children with special needs, without unduly sacrificing their own needs. Can, for example, a child with a walking problem, be a scorekeeper in a baseball game? Can this child have a turn at bat with someone else doing the running for him, so that the game is not compromised?
To sacrifice the needs of non-disabled children for the sake of a disabled child, will ultimately lead to resentment. Real friendship between non-disabled and disabled children has to allow both to get their needs met.