Sup fam, why is SO2 a stronger reducer than Cr3+?

When it acts as a reducing agent it is oxidised with the sulfur going from S4+ to S6+

Now on Cr3+, to be a reducing agent it has to be oxidized to CrIV, CrV, and CrVI. All of those are oxidizing agents, which want to gain electrons. As a result, the move from CrIII to CrHigher requires much energy, the compounds are not typically easy to form, and are unstable. CrVI compounds are toxic and cause cancer by altering cellular DNA in their oxidation reactions.