The author of Ṛgvedic Legends Through the Ages, H. L. Hariyappa, believes that interpolations are parts and parcels of human life so cannot be considered a crime.
Verses wherein Śunaḥśepa's name is mentioned:
(a) They say that to me by night and by day, and the same sentiment strikes
my heart (mind) as well. May Varuṇa the king, to whom Śunaḥśepa in bonds
addressed himself, liberate us. (RV 1.24.12)
(b) To three stakes bound, Śunaḥśepa has verily addressed himself to the
son of Aditi (Varuṇa). May Varuṇa the king set this (suppliant) free, may
He, (who is) wise and above restrictions, entirely remove the fetters. (RV 1.24.13)
(c) You did liberate the fast-fettered Śunaḥśepa from a thousand fold stake
and he became pacified, indeed. Even so do you, O Learned Priest of the
gods, Agni, sitting here (with us) loosen our bonds. (RV 5.2.7)
On a close study of the above verses, certain impressions are irresistible. The
first two verses which are ascribed to Śunaḥśepa do not seem to be his at all from
a rational point of view.
The legend depicts that these mantras were uttered by Śunaḥśepa in order to obtain release, whereas the two verses, just referred to regard the release as a thing of the past.
If scholars believe in the theory of interpolation as an important and inevitable
factor in textual criticism, then there can be no reason to demur at this conclusion,
namely, Śunaḥśepa did not compose the two mantras (RV 1.24.12 and 13), but a later
poet, possibly the compilers of the Śatarcina maṇḍala. Interpolation is a natural
instinct in man and as such cannot be considered a crime.
Considering the texts which have been transmitted for centuries by oral tradition only–viz. the Veda and Vedic literature–the aspect of interpolation need not be doubted at all, "for the organs of tradition were not machines, but men."
It is well-known that many verses and hymns have formed part of the later
Saṃhitās of the Yajus, Sāma and Atharva-vedas. Many a variant reading has
been noticed of the Ṛgvedic text. Such a thing could be detected because of the
availability, of the different recensions. In the case of the Ṛgveda, only the Śākala-Saṃhitā is what we have now. Who knows what Bāṣkala and others would
have revealed in a crucial passage like this?