Srila Prabhupada- The younger brother of desire is anger. If one’s desire is not fulfilled, the younger brother, anger, follows. Here we can mark that even great saintly persons like the Kumāras were also angry, but they were not angry for their personal interests. They were angry because they were forbidden to enter the palace to see the Personality of Godhead. Therefore the theory that in the perfectional stage one should not have anger is not supported in this verse. Anger will continue even in the liberated stage. These four mendicant brothers, the Kumāras, were considered liberated persons, but still they were angry because they were restricted in their service to the Lord. The difference between the anger of an ordinary person and that of a liberated person is that an ordinary person becomes angry because his sense desires are not being fulfilled, whereas a liberated person like the Kumāras becomes angry when restricted in the discharge of duties for serving the Supreme Personality of Godhead.

(SB 3.15.31p)