The CTA cannot be saying Dorje Shugden is sectarian anymore! These thangkas were produced way before the ban was imposed. Besides, it is a practice of 400 years history, how come 400 years ago no one complained about Dorje Shugden being sectarian and was an evil spirit?
No one will paint an evil spirit and worship it along with other enlightened deities. Having Dorje Shugden painted together with other protectors such as Palden Lhamo, Setrap; and Buddhas such as Amitabha, Shakyamuni, Tsongkhapa, etc., it must mean he is not an ordinary being. He was also seen painted with high lamas of different traditions. A high lama would not be propitiating a local deity or spirit, that is for sure.
What does the CTA have to say about Dorje Shugden being an evil spirit and sectarian now and causing them to lose their country? The reason they lost their country was that their corrupted government was not capable. During the Qing dynasty, they had to kowtow to the Qing government to get their protection. So if the Tibetan leadership was capable of running a country, why would they need protection from the Qing government? The Tibetan leadership in the past was incapable, now they are also incapable. Just accept the fact and be protected by the Chinese again, life will be much better.