I was rattling round on 26×1.95 tyres 10 years ago and survived.
Why does he need wide tyres? What is the problem you are trying to fix?
Only 10 years ago, was that with stabilisers too?
I used to ride 16″ x 3/4″ solid rubber tyres 30 years ago, I also survived.
As to why he needs them, he doesn’t need them he just wants wider tyres because his daddy has wider tyres and his daddy rides a rigid 29er+ single speed.
As to the problem, there is no problem. Fatter tyres just look better and give a more comfortable ride.
These things I know becuase I’ve been riding and building bikes for 30+ years.
Things evolve and improve….most things do, some things obviously don’t.