I understand full well how the world works in terms of how society views men with long hair versus men with short hair. However, I advocate that people broaden their scope when it comes to writing someone off based on their appearance alone. Employers should focus on performance and experience versus policing someone's hair when hiring.
The line itself for "clean and kept" is incredibly vague as well. This results in all types of hair that deviates from the norm to be considered unprofessional. An example of this is traditionally Black hairstyles like dreads being banned from the workplace because it isn't "clean and kept."
This type of mentality hurts people that legitimately go out of their way to practice hair maintenance. Hair length is not indicative of one's own personal hygiene and self-care. Allowing yourself to cloud your perceptions with antiquated mindsets does no good.