Why was Chanakya's untying of hair-knot (Shikha) so iconic?

Today, an orthodox Hindu, especially brahmin priests, keeps his head shaven except for a lock of hair called 'Shikha'. This tradition has been in place throughout India since at least 2 millennia.

Brilliant like a streak of lightning set in the midst of the blue rain-bearing clouds, slender like the awn of paddy grain, yellow (like gold) in color, in subtlety comparable to the minute atom, (this Tongue of Fire) grows splendid. तस्याः शिखाया मध्ये परमात्मा व्यवस्थितः । स ब्रह्म स शिवः स हरिः स इन्द्रः सोऽक्षरः परमः स्वराट् ॥

This is one shloka (verse) from Narayan Sukta, found in Yajurveda - one of the four Vedas, the most ancient Indian literature. (translation courtesy: https://sanskritdocuments.org/doc_vishhnu/narayana-sukta.html?lang=sa)

Anything that has been in tradition for so long is bound to build a meaning for itself. Now the tieing and untieing of the Shikha may have had different meanings at different times and at different parts of India, but it sure had a significance. Even today, Tieing of Shikha is considered mandatory for brahmin priests while reciting mantras at Yagya or religious ceremonies, etc. According to a book (by a leading publication named 'Gitapress' of books related Hindu religion and literature) of guidelines to 'Nitya-karma' i.e. regular rituals, 'Never perform any of the following activities without tying the Shikha: Bath, Charity, Japa (chanting Mantras), Homa (fire rituals), Sandhya (daily rituals) and Devata Puja.' In that context, Chanakya's vowing not to tie it until his enemy is destroyed seems to have meant that Chanakya vowed not to undertake any other activity unto himself but devote himself solely to the goal of his goal. Chanakya's untieing of Shikha is mentioned at least in Kathasarisagar and Mudrarakshas. The Buddhist sources, however, mention that he broke the sacred thread (janeu) instead of untieing of the knot. Janeu is another important symbol of an orthodox Brahmin and breaking it speaks the same message as untieing of the har-knot - not to weaver from the one goal of destroying the Nandas.

The author is the chief researcher and script editor for Glimpses videos.