I have spoken to anti DS people many, many times on this issue and all of them have the same approach and same reply: That the Dalai Lama said so, so therefore it must be true. When questioned further and provided with facts, they will start to break down and get defensive with the whole thing. They are unable to refute my points when i tell them that Dorje Shugden is actually enlightened and that they should come up with more proof that is not based on hearsay. Sadly, no one so far has been able to come up with proof that is solid, or has not shut me off with their claims that my information is incorrect. Most of them just dismiss the reasonings as propaganda in a very one sided, but they dont realize that they are doing the exact same thing too. And most of the time, these anti Dorje Shugden people just refuse to talk about the issue when they are being challenged with logic like how can Dorje Shugden harm the Dalai Lama when the Dalai Lama is a pure monk who holds his vows, the Buddha has declared that those who hold vows will not be harmed by spirits, so if Dorje Shugden is a spirit, why should they be afraid of him? If you pose this to most anti Dorje Shugden people, they will try to shut up the topic as deep down they know they do not have any basis for what they "believe" in.
Most of the people who go against Dorje Shugden have very little understanding of Buddhism and its basic topics of the 3 principle paths, Karma, merit, samaya, Guru devotion etc etc, they are in Buddhism for the wrong reasons and they lack understanding and refuse to study. That is why till this day, you do not hear anyone who is gelug, who is anti Dorje Shugden a prominent master. Dharma centers who adopt this policy tend to become stagnant or degenerate where less and less people go to them, or the followers give up Dharma altogether. I am sorry but they are not even real Buddhists to begin with if they lack all the basic info that they need to be Buddhist. But then again, not investigating and just laying back and accepting everything without investigation is definitely easier.