The object of this shravaNa is to obtain mukti as nirguNa-brahman right where you are without having to go anywhere. Inferior to this is the union with saguNa-brahman by going to Brahma-loka along the path of the Sun.
Even for that, according to Mundakopanishad (1.2.11) a mature Jiva – who is learned and also accomplished with the qualities of shama, dama, etc. has to leave home, go to the forest, and do penance, living by bhikshA. So does it not mean that one who receives the teaching on NirguNa-brahman has to take SannyAsa first?
The next mantra talks about him. He examines the whole world-experience and decides: "Everything revolves around karma. Our goal of the Atman will not be accessible to/by any karma. So let me abandon all karma". In other words he is ready to take up SannyAsa. But it has to be done only through a guru.
So he goes in search of a guru. The words ‘only through a guru’ is because of the emphasis *guruM eva* in the Upanishad. The Acharya explains why *guruM eva* occurs there: "Even a scholar who is knowledgeable on everything should not make his own efforts and hope to independently obtain Brahma-jnAnaM".
Later in the same Upanishad (III-2.4) it says, ‘It is not only by a man devoid of spiritual strength or a man overcome by delusion that the Atman is unattainable, it is not attainable even by one who is doing the austerities but who is ‘alinga’, that is, one devoid of the symbol that represents sannyAsa’.
This is the way the Acharya comments on the word ‘alinga’ in the Upanishad.