A rose by any other name....
While I have read of it still being done in warmer climes than here up noth, I can't see any way that it would either prevent spoilage by bacterial/fungal infection or keep flies or other insects away. About the only thing I can think of is that the strong and (to me) unpleasant flavor of too much black pepper might help to disguise the off flavor of meat that had begun to spoil. I have also heard of a similar and (again, to me) more palatable but equally questionable practice of using hot red cayenne pepper. In general, the strongest spiced foods traditionally come from areas with very hot climates where meat spoils very quickly. Before refrigeration, there were few alternatives that actually worked: drying, salting(corning), pickling, smoking, canning, all of which had differing degrees of effectiveness that were improved upon over time, especially as increased understanding of the principals of chemistry, physics, and biology yielded modern chemical preservatives and irradiation techniques. In terms of what actually might work, layers of cheesecloth and canning salt seems the most practical alternative to temporarily retard the spoilage process, absent a suitable way to chill it.