Sand is acceptable as a soil texture additive if it's clean, washed sand, but it is not ideal.
What you really want is Perlite, which is chunky light puffy white shit and completely inert- won't change the soil except by making it lighter.
I can see why an older grower might still use sand; it is commonly added to garden soil that is too heavy and clay-ey, but your friend should definitely try a grow with perlite instead- he will be pleasantly surprised.