Yol mo bsTan 'Dzin Nor Bu was a Tantirka (ngakpa) in the early 17th century in Tibet. Recognized as the third Yol mo tulku, he was closely associate with the Chang (byang) Ter lineage, one of the six main lineages in the Nyingma School. Benjamin Bogin's 2005 PhD thesis at the University of Michigan includes research, analysis and translation of his nam thar and other writings, and explores important issues surrounding the 'monk/nun vs. ngakpa/ngakma' question within Tibetan culture.
It was and still is common for tantric practitioners--ngakpas and ngakmas--to begin their spiritual lives and training as monks and nuns. After a relatively remarkable and eclectic academic training where he was regarded as something of a savant, Yol mo bsTan 'Dzin Nor Bu decided to relinquish his monastic vows and trappings and take up the conduct and practice of a ngakpa. His writings include interesting commentary on the change from the trappings and observances of a monk to the robes and ornaments of the ordained tantrikas; apparently this was the subject of monastic derision even in those times:
Other than a very few, nobody was pleased. The severity of my crime was considered worse than that of killing a person. To my face, everyone in all directions struck me with harsh criticism.... Just for a change of clothes, many people turned their faces.... [People said,] "Having let his hair grow and changed the color of his robes, next he'll take a wife. Later, he'll make a child. He'll drink chang carelessly." Still, [this] is all in agreement with the discipline of Shakyamuni. It's also [in] accordance with the tantras of Vajradhara and the secret instructions of [Padmasambhava]. For me, it fits very well. For others, [it is better] to remain [as monks.]
Later in his life, in the introduction to his The Daka's Roaring Laughter: An Exegesis of the Dreadlocks Worn by the Yogins Who Practice the Secret Mantra, Yol mo bsTan 'Dzin Nor Bu says:
Merely seeing the holders of the wisdom-mantra with their hair tied up in a top-knot and wearing white robes, [critics] minds blaze with anger like violent flames. The shouts of their baseless slander resound like echoes. Seeing that without a doubt this slander of the view and conduct of the secret mantra will lead to hell, unbearable pity for those people arose. Therefore I composed this brief explanation of the appropriateness of this comportment.
In defense of the view and display of the Tantrikas, Yol mo bsTan 'Dzin Nor Bu even quotes a text from the Nyingma Gyud Bum entitled The Black Dreadlocks Weapons of Battle Tantra. He then goes on to say:
If you say that it is not appropriate to wear the accoutrements of Heruka (trak tung) until one has attained the level of Samantabhadra or Vajradhara, then it follows that it is not appropriate to shave one's head and dye one's robes until the level of Sakyamuni is attained.
As Bogin observes: Worn properly, the robes of a monk or a [ngakpa] are not symbols that affix a social or religious meaning to the wearer; but rather the wearer becomes coterminous with the robes, the shaved head or the dreadlocks, container and contents become indistinguishable, crystal clear.