Calling India a US ally is quite a stretch. I'd say they're solidly neutral and not part of any major power bloc. If anything they were closer to the USSR during the Cold War, and their air force is MiGs and Sukhois.
Also I played Russia back when /s/ModernPowers used to play games and got shut down on improving relations with India because it was too unrealistic at the time. I've looked into this, and others on the site have, so I'm all ears to other reasons. Maybe I can disqualify a post invalidation if you got a good reason
Because those are cheap aircraft. The US sending and selling arms to India has been a long standing practice for that former British colony. They only relatively recently increased purchase of Russian military equipment.
Russia only has one operational half aircraft carrier....why would you buy one lol. Also Russia is Pakistan's primary weapon supplier, India is a US ally. Just gross incompetence to even try that lol