One day Tokusan went down toward the dining room, holding his bowls. Seppo met him and asked, "Where are you off to with your bowls? The bell has not rung, and the drum has not sounded." Tokusan turned and went back to his room. Seppo mentioned this to Ganto, who remarked, "Tokusan is renowned, but he does not know the last word." Tokusan heard about this remark and sent his attendant to fetch Ganto. "You do not approve of me?" he asked. Ganto whispered his meaning.
Tokusan said nothing at the time, but the next day he ascended the rostrum, and behold! he was very different from usual! Ganto going towards the front of the hall, clapped his hands and laughed loudly, saying, "Congratulations! Our old man has got holds of the last word! From now on, nobody in this whole country can outdo him!"
My interpretation differs from Sekida's, though I seem somewhat aligned with Mumon's comments. He refers to Tokusan and Ganto as 'puppets on a shelf' who have 'never dreamed' of the last word.
I sensed a thread in this koan relating to responding or being baited. Tokusan is chastised for doing something before 'the bell has rung' or 'the drum has sounded'. After being chastised, Tokusan returns to his room. He is also sensitive to Ganto's criticism, responds to it, and is influenced enough by it so that 'he is very different from usual'. However, the gossipy tone of the characters in the koan does not suggest to me that the criticism is something that should be taken seriously. It's more envious (he's famous, but he's not so great).
Tokusan's reactions to all these stimuli and his subsequent concern about Ganto's approval demonstrate a tendency to be controlled by the actions of others or to be pulled and pushed by the currents of the world. Ganto's final comment sounds like sarcasm to me. Tokusan may have achieved a last word as in 'having the last word', but he is not enlightened in his behavior. He will only be right-minded when he is free of the influences around him. The 'no one can outdo him' seems to be an ironic comment. You can win the battle and lose the war.
The point is that we must avoid being swayed and deluded by the actions and words of others. Only by disciplining our minds so that we are not pushed and pulled by random stimuli can we be in control and be free.