Aksionov possesses a couple of reasons for not seeking revenge upon Makar. The first is that when Aksionov arrived in the gulag, he began building a reputation for himself as a spiritual, calm, wise mentor. Perhaps after all those years of fulfilling that role, Aksionov realizes that he must "practice what he preaches." As he considers telling the guards that Makar is the one who is plotting an escape, he recognizes that it will do him no good and that perhaps it is up to God to reveal the truth about Makar.
Another motivation for Aksionov's pacifist attitude toward Makar is that he has been in prison for so long when Makar confesses to committing the crime that Aksionov is imprisoned for that the protagonist knows that he has nothing to return to in his hometown (his wife is dead, and his children were so young when he left that they would not remember him). Aksionov--like so many other longterm prisoners--has become more comfortable with his role in the prison that he does not desire "freedom" any longer. He is similar to the characters in The Shawshank Redemption by Stephen King. At the story's end, Aksionov tells Makar,
" 'God will forgive you! . . . Maybe I am a hundred times worse than you.' "
His words demonstrate not only his peace with himself but also that he has learned that God will enact justice in his own timing.