The comb is an argument, and the argument is with a figure the Punjab knew well. The renouncing ascetic of the Indian tradition leaves the household, abandons grooming as an attachment, and lets the hair mat into jata, sometimes ash-covered, as a visible statement that the ordinary world has been left behind. Uncut hair on such a man means withdrawal.
Sikh teaching keeps the uncut hair and rejects the withdrawal. The Gurus taught a discipline lived inside the household and the working world, summarised in the three instructions to work honestly, to hold God in mind, and to share what is earned. Hair that is uncut and also washed, combed twice daily and bound under a turban says exactly that: the body is kept, the world is kept, and the discipline is carried out among other people rather than away from them. Cleanliness is treated as part of devotion rather than as a distraction beneath its notice.
In practice it is also the least contested of the five. The kirpan raises questions at airports, courthouses and school gates in a dozen countries, and litigation about it has produced case law. A small wooden comb raises none, and it is carried through the world without comment by people whose other articles of faith are examined regularly.