I took my 11 and 13 year old kids there last summer and they were fine. A little bit of a stretch distance wise, and a couple of sections they walked, but I’d say if your 10 year old is into it- no worries. But, another idea is the same company does another run- mills peak, that is shorter and mellower. I’d say start with that. It is same area, but shorter and easier. If he likes that, can try the full downhill. Just make a day of it and take lots of breaks