This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
The exact historical development of 鬉 is uncertain. It visually contains 髟 (hair) and 㚇, but the original semantic and phonetic roles are unclear.
The top 髟 suggests hair, and the bottom 㚇 looks like a tangled bundle. Picture a messy mane of hair that is hard to untangle.
For ソウ, imagine a tangled mane of hair that needs a thorough combing: 'so' tangled it needs a 'sow' (ソウ) of patience to brush out.