This is a tough one for me. I grew up playing outside daily with my sister on our family farm. My husband, a city boy, spent his days riding bikes and playing with neighborhood kids. We both knew that it would be important to us for our kids to have lots of free time outside.
Let's be clear: There is no possibility of Collin playing outside alone.
I am not even slightly concerned about Collin being abducted. Those kinds of risks don't enter my mind. He just cannot be in an uncontrolled environment without me or someone who knows him equally well. He can't protect himself in any way from plain old danger: he can't get away from it, he can't call for my help, and most of the time he can't even detect it.
There are lots of reasons why the parent of a child with a disability might not be able to let him play outside alone. Vision issues, behavior issues, medical issues. I don't have a study to back it up, but I'm here to tell you that for some kids, the risk of playing outside alone IS incredibly high, regardless of any benefit they might receive.
But. (You knew that was coming.)
I still think risk (of a sort) is important. I still think independence and exploration and play - however they might look in a given case - are vital to health, development, and happiness. Maybe a child can't devise his own adventure, but he can still HAVE adventures.
No, Collin can't ride his bike by himself. But when we go down a hill, he FLIES down that hill, his parents running to keep up. His dad has even started taking Collin off-roading on the tricycle. They get a running start across a parking lot and then careen down a grassy hill out into a field. Collin can barely breathe through the excitement.
No, Collin can't go "play pretend" outside as my sister and I used to for hours on end. But he can participate as fully as possible in anything someone else cooks up. Want to make art with sidewalk chalk? Sure, he'll try that. Want to have a picnic? Collin loves dining al fresco. Want to go on an imaginary safari? I bet he'll hear the animals before you do.
When your child needs so much help with even the smallest things, the line between adequately protecting and over-protecting him can be extremely fine. But it's a line worth exploring and staking out.