1. Modi is considered Other Backward Class which is a low caste. 
  2. Hindutva ideology according to Savarkar, who came up with the term, is that Hindu is a national identity not a religious one. Sindu became Hindu in Persian, and Indus in Greek. And the Sindu was a river. So the Hindutva ideology is in reference to the people on the other side of the Sindu river. This is why Hindutva literally translates to Hinduness. I understand that this doesn't always translate into religious tolerance of Muslims (yes, I say specifically Muslims) but that is because the RSS was formed to counter attacks on Hindus by Muslims in the 1920s. Hedgewar (Founder of Rashtriya Swayamsevak Sangh): A Definitive Biography by Sachin Nandha was a super informative deep dive into the BJP/RSS.
  3. Modi has a 70%+ approval rate even after more than 10 years in power. So his government is popular and the results of the BJP's power are hard to ignore in terms of the infrastructure and India now being the 4th largest economy.

Speaking specifically to this law I think the government is just setting up a back doors of sorts with the recent bomb attack in Delhi and the terror networks founds in India.