No child has a guaranteed right to play school sports. They do not have an entitlement to play exactly the same amount of time as everyone else. They do have the right to learn that not everyone's abilities are the same; that they aren't always going to be the best at everything; that some people are going to be better than they and to have more playing time; that everything in life is not always fair; and that it's not all about them.
To even consider a lawsuit in this situation is unbelievably inappropriate. And that's my opinion.