"Those Karma yogi who cut off the dualities that arise from karma and whose minds are engaged in atman, are always busy working for the welfare of all living beings, and are free from all sins and achieve happiness from atman anubhavam."
From the sloka 20, Sri Krishna has been telling the various steps a person gets while practicing Karma yoga and attains atman sakshatkaram. In that series this is the last step, Samadhi. After getting atman sakshatkaram, sarva bhuta hite rata = wants to do good to all living beings, Chinna dvaidha = cutting off the twin [ the likes and dislikes mentioned in sloka 20], yatatmana= he regards atman as bhogyam, bhogasthanam and bhogopakaranam [ sloka 24]. By mentioning the stages in sloka 20 and sloka 24, it is understood that all the previous Five stages have been mentioned here. Rsaya = [rushi] the Karma yogi who is trying for atman sakshatkaram, ksina = destroys, kalmasha = all blemishes [ the beginninglss karma and the papa/punya accumulated is referred to here as blemishes], labhante = gains , brahma nirvanam = the happiness of atma anubhavam. Such a Karma yogi as he gets atman sakshatkaram, runs after all the living beings needing help.