1. I will not speak about this issue as talking about it even online is not safe.
2. Soviet Union which was a permanent member of the UN was sanctioned pretty much for the entirety of existence, Russia despite being the world's 3rd largest military power is sanctioned and an international arrest warrant is in place against Vladimir Putin. Many of the top CCP officials and agencies are sanctioned.
India cannot afford any of these,it's still economically extremely fragile. Besides,Do you want India to have this sort of reputation? to be put alongside Iran,North Korea, Venezuela,?
3. Massacre of Hindus were carried out by terrorists like Babar Khalsa who are designated as a terrorist organization by the international community. Bulk of the Sikh terrorists were eliminated iduring the insurgency period.
4. It's easy to castigate communities if you do not understand the backstory. Sikhs are quite emotive about their religion because they have faced persecution since the very foundation of their faith.They faced a large scale massacre during partition where their women and girls were raped and murdered in large numbers
Harmandir Sahib to Sikhs is what mecca is to Muslims. The temple being damaged in a military operation and a lot of civilians dying in it send shockwaves across the Sikh community. It is in this context that the mutiny and all other things unfolded.