Kelsang Gyatso began his Shugdenism at the behest of Trijang Rinpoche, who taught that Shugden was a protector because the 11th Dalai Lama and the Chinese Emperor enthroned him as such.
The 11th Dalai Lama died when he was 17 (1838-1856). From Wikipedia, In 1849, at the age of eleven, he took the novice vows of monkhood. He was enthroned on 25 May 1842 and assumed full power on the request of his government on 1 March 1855. However, he died less than one year later, thus becoming the third successive Dalai Lama who died at too young an age to consolidate his power.
More authoritative sources would be the 5th, 13th and 14th Dalai Lamas, all of whom urged against worshiping the dangerous spirit, Shugden, whose purpose was to harm disbelievers in Shugden. (the 14th Dalai Lama is the current Dalai Lama)
Trijang Rinpoche respected the 14th Dalai Lama, and was one of his early tutors.
In contrast, Kelsang Gyatso instituted a cult against the 14th Dalai Lama that maliciously calls the him a Nazi, Marxist, dictator, murderer, hypocrit, human rights abuser, traitor, evil, Muslim, cruel, pig, false Dalai Lama, spiritual con man, one of biggest scams of the century, corrupt politician, CIA agent and that the Dalai Lama has inflicted more harm than those who have killed millions of people, tortured millions of people and raped millions of women in modern times alone.
There is not a hint of evidence that any of this campaign is true.
Trijang Rinpoche NEVER taught such vile. There is no indication whatsoever that he thought such emnity. No one outside of the NKT sphere claims such vitriol.
Only Kelsang Gyatso and NKT ban the history, teachers and writers of Buddhism, creating in their place a distortion.
Love versus hate.