If we view the mongolian Geshe Namka Barzin as an ordinary sentient being, his accumulation of merit over his previous lifetimes & in his last human existence is a contributing factor for Him to become a retinue of Dorje Shugden even though it is not known whether he ever wished this or if he even know about Dorje Shugden at all. I believe that he had ever vowed to manifest as a Dharma Protector in one of his many lifetimes, nothing can happen without first planting a cause.
He died tragically without fulfilling his wish to be an ordained lama, but he ended up being part of the retinue of Dorje Shugden,who are responsible for protecting the pure doctrine of Je Tsongkhapa, he got more than what he had originally wished for!
Dharma practitioners should rejoice in his amazing good fortune.
May we all accumulate vast amount of merits for the same supra mundane miracle to happen for ourselves in this lifetime or in future existences.
On the other hand, he may be the emanation of a Buddha, manifesting as an ordinary human being, dying a tragic death,seeking revenge on his tormentors after death, & terrorizing the area before being subdued by a high Lama.