गोविन्द भाष्य (श्रील बलदेव विद्याभूषण - अचिन्त्यभेदाभेद वेदान्त ब्रह्मसूत्र भाष्य सटीक)

kṣatriyatvāvagates cottaratra caitrarathena liṅgāt
kṣatriyatva-status of being a kṣatriya; avagateś-from the understanding; ca-also;
uttaratra-in a later passage; caitrarathena-with Caitraratha; liṅgāt-because of the
sign.
That he is a kṣatriya is understood from the clue related to the caitraratha.
Purport by Śrīla Baladeva Vidyābhūṣaṇa
Jānaśruti is understood to be a kṣatriya. He possesses religious faith and a host
of other virtues. He is very charitable. He gives charity generously. He is the ruler
of the people. For these reasons it is said that he is a kṣatriya. Because he sent (a
messenger to search for Raiṅka) and because he gave cows, necklaces, chariots, his
daughter, and many other things in charity, it is said that he is a kṣatriya. It is not
possible for anyone but a kṣatriya to possess these qualities. Because he thus
displays the qualities of a king, Jānaśruti should be understood to be a kṣatriya. At
the end of the story it is also understood that he is a kṣatriya. At the end of the
story, where the description of saṁvarga-vidyā is concluded, there is mention of
the kṣatriya status of a person named Abhipratārī Caitraratha. In the concluding
passage a brahmacārī begged alms from Śaunaka Kāpeya and Abhipratārī
Kākṣaseni when these two were serving food to others.
If someone objects: "In this passage the status of Abhipratārī as either a kṣatriya
or caitraratha is not proved in any way," then the sūtra answers: liṅgāt (because of
a clue). The clue that Śaunaka Kāpeya and Abhipratārī Kākṣaseni were friends
proves it. The Tāṇḍya Brāhmaṇa (20.12.5) says: caitena caitrarathaṁ kāpeyo
ayājayan (The members of the Kāpeya family made Caitraratha perform a
sacrifice). In this way the śruti maintains that because of his relationship with the
Kāpeyas, Abhipratārī must have been a Caitraratha.
That the Caitraratha family were kṣatriyas is confirmed by the words tasmāc
caitrarathir nāma kṣatra-patir ajāyata (From him was born another kṣatriya of the
Caitraratha family). In this way his kṣatriya status is clearly proved.
Therefore Śaunaka Kāpeya and Abhipratārī Caitraratha, who were both learned
in saṁvarga-vidyā, were a brāhmaṇa and a kṣatriya respectively, and in the subject
of saṁvarga-vidyā they were also guru and disciple respectively. Raiṅka and
Jānaśruti had the same relationship, and therefore Jānaśruti must have been a
kṣatriya. In this way it is proved that a śūdra is not qualified to study the Vedas.
Referring to the śruti, he again establishes this point.
Sūtra 36