India watching US for sanctions on Turkey

The issue is not the same.
It was never about Turkey buying the S-400 per se, it was about Turkey buying the S-400 AND the F-35, a system designed to penetrate air defenses of that ilk. Owning both, Turkey would be able to glean all sorts of intelligence on the strengths and vulnerabilities of the F-35 vs the S-400, and that would have been extremely valuable to countries like Russia.
India has no F-35 or other stealth platforms, so it is much less emergent that we worry about where they buy air defense systems from.

Another ally buying weapons from our adversary. So much winning.

So not mentioned in the article is this very key piece of information. The AS-400 system like our THAAD is also used for nuclear missile defense and unfortunately India has to worry about China advancing Nuclear Pakistan's missile technology. I am pretty confident that is the major reason for the AS-400 and that the United States was unwilling to sell the THAAD to India (so in that respect, India had little choice on that contract). On the license building of T series tanks, India has been doing that since the T-62 or T-72 I believe with the Russians. They are comfortable with the Russian MBT and probably do not want to pay to change at this point. Also, the Russian tanks are much cheaper per copy than the American tanks. If you have over a Billion in population in Asia, human life is cheap and the philosophy is the population will just birth more. So survivability of each tank is not a huge concern over the numbers of tanks that can be fielded. Another reason why they would not buy an American tank. In India you can kill someone via what you would be charged with manslaughter over here in the United States. Over in India, just an exchange of settlement money , people shake hands and nobody goes to jail.