The reason for this anger is the fear of losing control of the narrative. By keeping the Sanskrit scriptures arcane, they can build their own narratives around it. But when scholars start studying those text, the cat will be out of the bag.

They may feel that it is harmful to the Hindutva interests when scholars write about the procedure for cow sacrifice mentioned in Yajur Veda or the racism and misogyny perpetuated by Manu Smriti or the Soma drinking revelry in Rigveda.

These efforts to stop others knowing these scriptures are happening since pre-historic times and even codified in Hindu Law.

Dharmasutra says "If he (Sudra) listens in on a vedic recitation, his ears shall be filled with molten tin or lac; if he repeats it, his tongue should be cut off; if he commits it to memory, his body should be split."[1]

Dharmasutra, written circa 600 BCE, is a book on Hindu Law and Sudra is the lowest class in the Varna system.

The ban on Wendy Doniger's book in India is a case in point.

References:

[1] https://books.google.com/books?id=gnVxqvPg9a0C&q=lead#v=snip...

[2] https://www.sacred-texts.com/hin/manu/manu05.htm

[3] https://www.tribuneindia.com/news/archive/features/a-few-rea...

[4] https://en.wikipedia.org/wiki/Wendy_Doniger