They at least organised themselves didn't they? How else did three of them (four if we count John Doe) end up in court together on the same charges?

Yes shareholders did call the DEC. They were calling to get up-to-date, accurate information. They weren't calling to report black smoke emanating from the plant (while the DEC was on site, no less!) or the placement of ladders. Nor were they calling to complain about couches & BBQs on the back porch or pretending to be experts on paint colours at the blending plant, as some were.