Ductile materials typically have the same tensile strength and compressive strength. Also yielding is the criterion of failure in ductile materials. In maximum shear stress theory, it is assumed that the yield strength in tension is equal to the yield strength in compression. Also, the criterion of failure is yielding.
Therefore, a maximum shear stress is used for ductile materials.
If the mean principle stress is compressive, then distortion energy theory should be preferred.