It very well could be possible that he is both gifted with ASD, like my little boy.
A couple of things you have said ring alarm bells with me. Including guiding a persons hand to complete a task like a puzzle. I am not sure if you are aware but it is a very typical thing for some autistic children to do.
My little one was similar to yours. He had mastered the world map at 13 months old, doing 300 piece puzzles at 2, amazing mathematical abilities at 2. Taught himself to read like an adult at 3. He has just turned 4 and is amazing.
He has Aspergers and is gifted >99.9
So children can be both. Not being able to follow instructions is a concern. Being refered to have this done says to me that there are clear traits. Given the family history Id be preparing myself for that diagnosis.
I understand why you wouldn't want to give him therapy unless he absolutely needs it, I just want to reassure you that if you do get a diagnosis. Run with it. Give him as much as possible because like my son he will thrive. Being smart will enable him to learn and learn quickly.
Best of luck
