It is okay to keep a 7 year old boy in diapers full time and not potty train him.
Diapers are better than using the toilet and healthier as well.
I would also babysit 7 year old boy who still wears diapers full time.
I would babysit any kid of any age who wears diapers full time or any time and I would be glad to change their diaper as well.
If I babysit a kid they will be in diapers at my house and not allowed to use the toilet.
Here's some cute diaper boys that I wish I could babysit.