I am not into high power BR scopes, especially very fine hairs and such small dots. Maybe he should try something with an illuminated reticle. At least he might able to see the hairs and dot against the black bull better.
(I say) Caliber be damned. Seeing the target (and the reticule) is what counts, IMO.That's a tremendous amount of scope for a 22 rimfire. The handicap with his scope is with the dot. What he probably needs is a dual X type reticle. Even if he can't see the fine part of the crosshairs, the heavy ones are enough that all he needs to do is center it on the target and touch the trigger off. Might show him one of these Weaver Classic Extreme scopes.