We stopped high sulfur when we realized it was causing acid rain. CO2 is also acidifying the oceans, so there aren't a lot of things we can pump into the atmosphere without consequence. Best to avoid doing that altogether.

I would a well. Unfortunately, it seems that deliberate geoengineering always brings up concerns from people who think it's more ethical to just state at the lever as the trolly goes by. I partially blame the legal system. There won't be a lawsuit about not having deliberately spread more sulfur oxide.