No, Namkha Barzin is not fully enlightened. He is the spirit of a Geshe, and is among the "youngest" members of DS's entourage, having joined only about 60 years ago.
There has been a thread about this previously about the nature of Namkha Barzin and other protectors.
A further explanation here:
Domo Geshe Rinpoche tamed even more intractable beings. In the 1920s a Mongolian Geshe returned from pilgrimage in India and stopped at Dungkar Gonpa on his way to Lhasa. Rinpoche was away at the time and Umdze Sherab, who later became the famous abbot of Dungkar Gonpa, asked the Geshe to stay, as he had a high fever and was too sick to travel.
But the Geshe did not accept the invitation. He wanted to be in Lhasa for the Great Prayer Festival (Mönlam Chenmo). On the steep road to Phari, he reached the end of his life. He sat down next to the road and the death process started. The Geshe did his practice, which was not completed when several Bönpos arrived. Well intentioned, they performed the transference of consciousness, since the dying man had stopped breathing.
This interrupted the Geshe's practice on the most subtle level of consciousness and he turned into a raging spirit who killed many Bönpos in Tromo. Several Buddhist practitioners tried unsuccessfully to appease the fury of this being. When Domo Geshe Rinpoche returned, he tamed the ferocious spirit, put him under oath, and called him Namkha Bardzin. He became a special protector for the area of Tromo.
Source: Biography sketch of Domo Geshe Rinpoche which was written by Ursula Bernis in 1995, initially for inclusion in a compendium of biographies of great Gelugpa masters, http://www.nyackbuddhism.org/rinpoche.html*****************************
The original thread can be read here:
http://www.dorjeshugden.com/forum/index.php?topic=695.0