I don't disagree with you on the technical merits... it still IS a cut cancel, but the marketplace does seem to value them differently when they don't break the surface of the paper. Perhaps not the same valuation as truly uncut, but something between cut and normal Scott values (ignoring normal discounting from Scott for the moment).
In other words, for the uninitiated, don't automatically circular file a cut cancel that doesn't break the surface.

Actually, now that I think about it, don't ever can a cut cancel or perfin cancel on a 20th-century revenue without checking Scott first, especially high denominations.