I agree, study of history is important ,even though it was a subject I hated in school because of the way it was taught (memorising dates and this and that dynasty).
However history has to be studied openly -not only from the point of view of the ruling party.
Why did Shan attacked PJ Thum so fiercely on March 2018 , the last day of the sitting of the Select Committee on Deliberate Online Falsehoods?
I quoted the below from Wiki
"...….....170 academics...……. criticised the hearing as an attempt to attack and destroy Thum's credibility and discredit his research, with the effect of stifling the freedom of expression and academic freedom in Singapore A letter from six of Thum's colleagues at the University of Oxford's Project Southeast Asia also expressed concerns about how Thum was treated at the hearing, saying that Thum's research, which Shanmugam had criticised, had "already met the rigorous standards of examination at Oxford and peer review by fellow historical experts on the region". The letter also expressed concerns about the "implications for academic freedom, and for freedom of expression in Singapore", saying that the hearing "appears designed to intimidate those who seek to publish the truth".