The FAA appears to have made the VDP regulatory via the AIM (p. 5-4-18):
The VDP is a defined point on the final approach course of a nonprecision straight-in approach procedure from which normal descent from the MDA to the runway touchdown point may be commenced, provided visual reference required by 14 CFR Section 91.175(c)(3) is established.
. . .
The pilot should not descend below the MDA prior to reaching the VDP and acquiring the necessary visual reference.
While some may not consider the AIM as regulatory, arguing that point to an investigatory board will likely yield you nothing...