Visual estimates can be quite subjective. "Disseminated" sulphides does actually have a strict definition as well (usually <0.25-0.5% modal abundance), and usually infers a specific process of crystallisation from isolated patches of melt surrounded by grains yielding non-wettable surfaces.
The chalcopyrite will also almost certainly be impure, <0.3-0.5% Cu for these types of deposits is pretty typical.
Given the lack of geological information released, I am assuming the model approximates an orthomagmatic mafic-ultramafic layered intrusion containing atleast one horizon that has experienced sulphur saturation (triggering precipitation of chalcophiles) - unsurprisingly, from their sections, this lies within the **bronorite-wehrlite contact. Ultimately, lateral (layer parallel) heterogeneity in metal endowment is to be expected as these sulphidic liquid segregates tend to pond together.
The most robust indications one can derive regarding whether or not to expect anything at depth is via geochemical anaylsis (chromite zonation, magma mixing horizons, evidence of silica or sulphur assimilation, etc.)
Lastly, the relative difference in distribution of chalcopyrite versus PGMs may or may not be influenced by the dykes present (they can induce selective remobilisation of sulphides)
Visual estimates can be quite subjective. "Disseminated"...
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