My best guess, putting myself into their shoes, is that this is a leftover variant from pecorino steaming. When pecorinos are steamed, it is done to ensure acidification. My guess is that someone was tired, made an evening batch of cheese in the fall because there was farm work, and woke up to an overacidified cheese. What the hell... let's age it out anyway. Turns out, it's tasty. Then the refinements came in to dial in this cheese specifically, preserving the warm period.
That area north of Milano is well suited to it because winter humidity is so high.