While more research will need to be done before something like this is actually done, especially on a massive scale, the idea behind it is present in nature already and has only few downsides. Considering that global warming, which is the main target of using sulfur dioxide, has the potential to do more damage to the ecosystem than releasing sulfur, then there appears to be no reason to reject the idea.
Solar shading is a new idea to combat global warming by injecting specific gases into the atmosphere in order to prevent as much solar energy coming to the planet. However, geoengineering does nothing to curb green house gas emissions, and other factors of climate change. It's putting a band aid on staph infection: makes it look better, but doesn't help the underlying problem.