Can you rely on the distance scale for older AIS lenses as an accurate measurement for hyperfocal distance? Or is this value skewed for Nikon digital SLR's because of the 1.5 crop ratio and therefore a different CoC vs Film.

The DOF markings on all Nikon MF lenses seem to have been based on a COC of 0.03 mm that traditionally was used for viewing an 8x10 inch print made from a 35 mm film frame. Because the image captured by a DX sensor is 2/3 the size, it must be enlarged 1.5X more to produce the same 8x10 print. Thus the COC generally used to estimate DOF for Nikon digital DSLRs is 0.02 mm.

Hyperfocal distance is approximately proportional to focal length squared, and inversely proportional to the product of aperture and COC. Strictly speaking, these proportionalities only apply when hyperfocal distance is much larger than lens focal length, but in practice that condition is always satisfied. Therefore, a 1.5X decrease in COC is approximately equivalent to a full stop (1.4X) wider aperture for DOF calculations. Therefore, you can use the DOF markings on a MF lens to estimate DOF and hyperfocal distance even for digital if you remember that you get about 1 stop less DOF when using a DX digital sensor, assuming focal length and distance are the same.

Since the usual comparison between film and digital is done at equivalent FOV, then the actual focal length used is different by the 1.5X crop factor, and images captured on a digital sensor have about about 1 stop more DOF.