The whole issue is meaningless. Because:
1 - He is a human being (a fact)
2 - He is the leader of Tibetans (a fact)
3 - everything else in him, is unproveable (a fact)
All the questions about whether he is or is not the "real thing" are meaningless, because the previously mentioned three points hold true in any event and anything beyond those three, is just imagination, an opinion, a view, or a social contract.
So in that same way, for the sake of discussion, I could say that
1 - Dorje Shugden is a spirit in the glass of Gyalpo (a fact)
2 - He has passed away (witnessed by many) and has taken rebirth as a spirit after being "murdered" by the followers of the 5th Dalai Lama, hence similar / no different than an ordinary gyalpo or tsen spirit who has an inferior form ( a fact)
3 - everything else in him, is unproveable
Why would anyone care, or even think about, whether Dorje Shugden is "this or that". For he is a spirit, that's all. There is no beyond.
Ah, but you
could not say that.
1 - Although Dorje Shugden is a non-material being, the issue of whether he is of this or that class remains disputable, not a fact. Hence all the hulabaloo. (In fact, most Buddhists do not even know what a gyalpo or tsen means, so these are hardly facts, even by general Buddhist standards, but just some Tibetan superstitious ballyhoo.)
2 - Drakpa Gyaltsen has passed away, yes, a fact, but we do
not know how he died or what happened to him afterwards, but since we are not making pujas to him but to Dorje Shugden, it does not matter. Drakpa Gyaltsen is a case of rumours, not facts.
3 - The cases of Dorje Shugden being in truth Manjushri, and Dalai Lama in truth Avalokita, are not facts, but religious beliefs, applicable only within certain schools of Buddhism.
But when it comes to the Dalai Lama, it is sure that he is a human being, since he has a mother with a womb, and a father with, well, a vajra. This is a fact. And whether the Dalai Lama is the leader of Tibetans, well, this is a fact, disputed only by Beijing. Whether he is a Bhikkhu, is not proven. Not a fact. But he is a human leader, factually. Maybe we could just see him in that way, through the facts, universally accepted and proveable. For his disciples who have received an empowerment, he is factually of course a Buddha, but that is not generally applicable view, nor an universally valid truth, but merely a tantric
view. Similarly, we hold Dorje Shugden to be a Buddha, because of the tradition of Vajrayana. For a Theravadin or a Zen practitioner, neither the Dalai Lama or our Dorje Shugden are Buddhas. This has to be understood. The view of them being Avalokita and Manjushri applies only within certain circles, not outside.
But to the question of
why would anyone care, or even think about, whether Dorje Shugden is "this or that", for he is a spirit, that's all, the answer lies in
not his alleged status as a Buddha or a demon, but in his status as a religious object of faith and worship. Of course the same could be said of the Dalai Lama, but then again, he is evidently, factually, a human leader of humans, so he is in a different class, when it comes to the Law, and the Freedom of Worship. He can and should be criticized, ousted and censured, if need be, as he is a human leader, but Shugden cannot and should not, as he is a deity.