I used to work with autistic adults. Parents would stitch them into coats, under shoe linings, tongues of shoes, even hair scrunchies. Very inventive. You can also key key ring holders for them that you could attach to most things like zips, belt loops, even clothes tags.
From toddler to around 6yrs old, my now adult son (autistic, has developmental delays and learning difficulties) was what we lovingly called a flight risk. All it took was a few seconds and he would be off like a whippet, both indoors and outdoors. I certainly couldn't catch him outdoors if he got too far away, so always used reins or his SN buggy until he outgrew them, then insisted he held my hand if we were near any dangers. I would only trust a very small handful of people to watch him, and they all knew him really well. One of them was my elderly FIL who loved taking him out, but knew the drill, had to be in his buggy. However he would still take him out and walk hand in hand with him. He never fell while holding his hand, but if he had, my son would have definitely ran off like Noah did.
I wonder if those of you being so awful and rude have ever had experience of a child with disabilities that is a runner? It's bloody hard, bloody challenging, and doesn't help seeing judgy faces or reading judgy comments like the ones you're posting. All it takes is a few seconds. Doesn't matter how or what the grandad looked like or was doing, those couple of seconds is all it took and his grandad no doubt will feel shit about it for the rest of his life.